“On the evening of that first day of the week, when the disciples were together, with the doors locked for fear of the Jews, Jesus came and stood among them and said, “Peace be with you!” After he said this, he showed them his hands and side. The disciples were overjoyed when they saw the Lord.” (John 20:19)
I don’t know what the disciples were doing before Jesus appeared to them for the first time after His resurrection. They were confused and afraid. Maybe they talked and argued all day long. At evening time they may have been tired and probably just sitting around. Then, all of a sudden there was Jesus. All the doors were locked. He just appeared.
When the disciples saw Jesus they rejoiced and believed at the sight of His glorified body with the nail prints in his hands and the spear wound in his side. They knew what they were seeing was no ghost, no figment of their imagination. This was Jesus in the flesh bearing the marks of His crucifixion. He was real. He had been beaten, executed and buried. Somehow, He had overcome death and risen from the grave. They had no clue as to how it happened, or what exactly that meant, but they were no longer afraid.
They were so filled with joy they needed no explanations or theological lectures. But they did need to know what to do next. So Jesus commissioned them to carry on His work. In order to do this, they needed supernatural power. Jesus gave them the Holy Spirit as He had promised the night He was betrayed. The Spirit gave them new life, power, strength, courage and abilities they did not possess so that they would do the same things Jesus did. The Holy Spirit still imparts His power to us today so we may continue the work of Jesus.