Heaven is the Spirit Realm. It is from where our Father issues because He is Spirit.
The Holy Spirit is the Father of our Lord Jesus Christ. .
A father is one who begets, who sires a being just like himself.
Hence, our Heavenly Father is the Holy Spirit who has begotten us as New Spirit beings.
The Holy Spirit exists in the Spirit Realm where also our New Spirit exists .
Note, Jesus said the Kingdom Of Heaven is at hand . He was telling us that the Spirit Realm is all around us and that the King of Heaven, Himself filled with the Holy Spirit, is here to do a work in and through us according to our Faith.
We are Born Again by Grace Through Faith in Christ Jesus. We are then eligible to receive (into our body) the Holy Spirit who comes to all who ask .
Jesus is the First Fruit of the Holy Spirit. We are Born Again by the Word and Holy Spirit so that we are fruit of the same root.
Our Heavenly Father is our spiritual Father who is the Holy Spirit.
Since the Holy Spirit who is our Heavenly Father is in us, we are seated with Christ in Heavenly Places even while we walk the earth in the flesh.