The first heaven I believe to be the air above us, the clouds and atmosphere.
Gen 1:1 In the beginning God created the heaven and the earth.
Gen 1:7 And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament: and it was so.
Gen 1:8 And God called the firmament Heaven. And the evening and the morning were the second day.
The second heaven is outer space, the planets, suns and stars.
Gen 1:15 And let them be for lights in the firmament of the heaven to give light upon the earth: and it was so.
Gen 1:16 And God made two great lights; the greater light to rule the day, and the lesser light to rule the night: he made the stars also.
The third heaven is in the spiritual, where Jesus Christ is the dwelling place of God and his angels.
A vision of being caught up to the third heaven.
2 Cor 12:1 It is not expedient for me doubtless to glory. I will come to visions and revelations of the Lord.
2 Cor 12:2 I knew a man in Christ above fourteen years ago, (whether in the body, I cannot tell; or whether out of the body, I cannot tell: God knoweth;) such an one caught up to the third heaven.
2 Cor 12:3 And I knew such a man, (whether in the body, or out of the body, I cannot tell: God knoweth;)
2 Cor 12:4 How that he was caught up into paradise, and heard unspeakable words, which it is not lawful for a man to utter.
We are not to know all about heaven at this time
1 Cor 13:9 For we know in part, and we prophesy in part.
1 Cor 13:10 But when that which is perfect is come, then that which is in part shall be done away.
1 Cor 13:11 When I was a child, I spake as a child, I understood as a child, I thought as a child: but when I became a man, I put away childish things.
1 Cor 13:12 For now we see through a glass, darkly; but then face to face: now I know in part; but then shall I know even as also I am known.
Prophetic vision, in the Spirit
Rev 1:9 I John, who also am your brother, and companion in tribulation, and in the kingdom and patience of Jesus Christ, was in the isle that is called Patmos, for the word of God, and for the testimony of Jesus Christ.
Rev 1:10 I was in the Spirit on the Lord's day, and heard behind me a great voice, as of a trumpet,
Our spirit is in heavenly places now, in Christ Jesus. Our body is working here for his glory. We are made complete in him, without sin, when we leave this earthly body and receive our heavenly body.
1 Cor 15:48 As is the earthy, such are they also that are earthy: and as is the heavenly, such are they also that are heavenly.
1 Cor 15:49 And as we have borne the image of the earthy, we shall also bear the image of the heavenly.
1 Cor 15:50 Now this I say, brethren, that flesh and blood cannot inherit the kingdom of God; neither doth corruption inherit incorruption.
1 Cor 15:51 Behold, I show you a mystery; We shall not all sleep, but we shall all be changed,
1 Cor 15:52 In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed.
1 Cor 15:53 For this corruptible must put on incorruption, and this mortal must put on immortality.
1 Cor 15:54 So when this corruptible shall have put on incorruption, and this mortal shall have put on immortality, then shall be brought to pass the saying that is written, Death is swallowed up in victory.
1 Cor 15:55 O death, where is thy sting? O grave, where is thy victory?
1 Cor 15:56 The sting of death is sin; and the strength of sin is the law.
1 Cor 15:57 But thanks be to God, which giveth us the victory through our Lord Jesus Christ.
Eph 1:3 Blessed be the God and Father of our Lord Jesus Christ, who hath blessed us with all spiritual blessings in heavenly places in Christ:
Eph 1:4 According as he hath chosen us in him before the foundation of the world, that we should be holy and without blame before him in love:
Eph 1:17 That the God of our Lord Jesus Christ, the Father of glory, may give unto you the spirit of wisdom and revelation in the knowledge of him:
Eph 1:18 The eyes of your understanding being enlightened; that ye may know what is the hope of his calling, and what the riches of the glory of his inheritance in the saints,
Eph 1:19 And what is the exceeding greatness of his power to us-ward who believe, according to the working of his mighty power,
Eph 1:20 Which he wrought in Christ, when he raised him from the dead, and set him at his own right hand in the heavenly places,
Eph 1:21 Far above all principality, and power, and might, and dominion, and every name that is named, not only in this world, but also in that which is to come:
Eph 1:22 And hath put all things under his feet, and gave him to be the head over all things to the church,
Eph 1:23 Which is his body, the fulness of him that filleth all in all.
Eph 2:1 And you hath he quickened, who were dead in trespasses and sins:
Eph 2:2 Wherein in time past ye walked according to the course of this world, according to the prince of the power of the air, the spirit that now worketh in the children of disobedience:
Eph 2:3 Among whom also we all had our conversation in times past in the lusts of our flesh, fulfilling the desires of the flesh and of the mind; and were by nature the children of wrath, even as others.
Eph 2:4 But God, who is rich in mercy, for his great love wherewith he loved us,
Eph 2:5 Even when we were dead in sins, hath quickened us together with Christ, (by grace ye are saved;)
Eph 2:6 And hath raised us up together, and made us sit together in heavenly places in Christ Jesus:
Eph 2:7 That in the ages to come he might show the exceeding riches of his grace in his kindness toward us through Christ Jesus.
Eph 2:8 For by grace are ye saved through faith; and that not of yourselves: it is the gift of God:
Eph 2:9 Not of works, lest any man should boast.
Eph 2:10 For we are his workmanship, created in Christ Jesus unto good works, which God hath before ordained that we should walk in them.
Eph 3:6 That the Gentiles should be fellowheirs, and of the same body, and partakers of his promise in Christ by the gospel:
Eph 3:7 Whereof I was made a minister, according to the gift of the grace of God given unto me by the effectual working of his power.
Eph 3:8 Unto me, who am less than the least of all saints, is this grace given, that I should preach among the Gentiles the unsearchable riches of Christ;
Eph 3:9 And to make all men see what is the fellowship of the mystery, which from the beginning of the world hath been hid in God, who created all things by Jesus Christ:
Eph 3:10 To the intent that now unto the principalities and powers in heavenly places might be known by the church the manifold wisdom of God,
Eph 3:11 According to the eternal purpose which he purposed in Christ Jesus our Lord: