"After this, we got ready and went up to Jerusalem. Some of the disciples from Caesarea accompanied us and brought us to the home of Mnason, where we were to stay. He was a man from Cyprus and one of the early disciples." NIV translation
God not only changed the hearts of the people in Caesarea in the previous passage but we see here that some of them even went on to travel with Paul. This is a good reminder that our testimony is a combination of our words and actions. The people there heard Paul's words before and now some are going to get to see his actions in the face of persecution. That will help them to grow in their faith. Mnason also reminds us that, as Christians, we should be ready to share our things (homes, finances, time, etc) with those who are fellow workers for the Lord.
"When we arrived at Jerusalem, the brothers received us warmly. The next day Paul and the rest of us went to see James, and all the elders were present. Paul greeted them and reported in detail what God had done among the Gentiles through his ministry." NIV translation
Paul made a courtesy call on the leaders of the church in Jerusalem. I say this because there are many who take his visit here and try to make a case for a certain "church" structure and even to go so far as calling a man on earth the "head of the church".
In Ephesians 1, Paul explained that God's will is for Jesus to be the head of the church and not a man here on earth. Paul worked with the leaders of the believers in Jerusalem but he was subject to Jesus Christ and listened to the Holy Spirit for direction. He simply informed them about what God had been doing in his life. (We would call this sharing a testimony.)
"When they heard this, they praised God. Then they said to Paul: 'You see, brother, how many thousands of Jews have believed, and all of them are zealous for the law. They have been informed that you teach all the Jews who live among the Gentiles to turn away from Moses, telling them not to circumcise their children or live according to our customs.'" NIV translation
When the leaders in Jerusalem heard about what God was doing in his ministry, they praised God but then had to inform Paul that not everyone was happy with his ministry. The thousands of Jews that believed were "zealous for the law" instead of zealous for Jesus as Paul was. Therefore, Paul was being falsely accused of turning people away from their customs. Paul was not doing that but was simply telling people that customs, rituals, or belonging to a particular group of people did not bring salvation. Sadly, we face many of the same issues today as legalism has crept back in and even taken over in some groups of believers.