When Jesus died on the cross, three days later He came to life again. He spent a lot of time with His disciples. Then He returned to Heaven (where He was before He was born as a baby). Here are the final words He said to His disciples before ascending. The words He told His disciples applies to us as modern day disciples (Christians). Basically it’s our duty to continue spreading the good news of Christ Jesus.
8 But you will receive power when the Holy Spirit comes upon you. And you will be my witnesses, telling people about me everywhere—in Jerusalem, throughout Judea, in Samaria, and to the ends of the earth.”
9 After saying this, he was taken up into a cloud while they were watching, and they could no longer see him. 10 As they strained to see him rising into heaven, two white-robed men suddenly stood among them. 11 “Men of Galilee,” they said, “why are you standing here staring into heaven? Jesus has been taken from you into heaven, but someday he will return from heaven in the same way you saw him go!”
In another account of Jesus’ life there are a few more details. Jesus is at the right hand of God.
19 When the Lord Jesus had finished talking with them, he was taken up into heaven and sat down in the place of honor at God’s right hand. 20 And the disciples went everywhere and preached, and the Lord worked through them, confirming what they said by many miraculous signs.