There are four accounts in Scripture that describe the apostles after Jesus' ascension.
-- Matthew 28:19 has the apostles going forth to make disciples of all nations.
-- Mark 16:20 says that the apostles "went forth and preached everywhere, while the Lord worked with them and confirmed the word through accompanying signs" sending them throughout the world proclaiming "eternal salvation."
-- Luke 24:52-53 says the apostles returned to Jerusalem proclaiming Jesus and praising God in the temple.
-- And the most detailed presentation is found in Acts 1 and 2, which describes the election of a new apostle to replace Judas Iscariot and the effects of the coming of the Holy Spirit on Pentecost.
In each of these four passages, the followers of Jesus are seen as strong, courageous and determined messengers. They have no doubt that they have been charged by Jesus to proclaim the good news to the world.
Nowhere after the ascension is there any indication that they were afraid to appear in public, and we see that the coming of the Holy Spirit gave them the courage to take up Jesus' mission. What Acts tells us is that when the tongues of fire came to rest on them, they became able to speak languages they did not know.