All you Christians believe that Jesus died and rose again-- then what happened to him after that\?

He was never heard from again

He went back to heaven. He is now the king of Gods kingdom ruling in heaven

Jesus was a MAN; Christ is the Son of God. Jesus' earthly body did not rise from the tomb; angels rolled away the stone and disposed of it as with Moses. Jesus appeared in The Christ body to satisfy our demand for proof he was from God. Peter, who was with Christ, and Jesus, on the MT. of Transfiguration, understood this but was advised not to reveal it.

he ascended into heaven

Rom 14:9 For to this end Christ both died, and rose, and revived, that he might be Lord both of the dead and living.

1Pe 3:18 For Christ also hath once suffered for sins, the just for the unjust, that he might bring us to God, being put to death in the flesh, but quickened by the Spirit:

He ascended in to heaven.

He was on earth for 40 days, was seen by hundreds, and then ascended into heaven.

He sits at the right hand of the Father on His throne.

Q.

He returned to the Father.

(But what does that mean?)

It means he left the temporal realm and returned to the transcendent realm.