Galatians 2:1

"Fourteen years later I went up again to Jerusalem, this time with Barnabas. I took Titus along also." NIV translation

So, Paul traveled around sharing the gospel and fourteen years later he went back to Jerusalem. The "church" in Jerusalem was made up of Jews and Paul took with him Titus who was a Gentile convert. We notice that Paul did not get his instructions, financing, or approval from the leaders in Jerusalem during those years.

Galatians 2:2

"I went in response to a revelation and set before them the gospel that I preach among the Gentiles. But I did this privately to those who seemed to be leaders, for fear that I was running or had run my race in vain." NIV translation

Paul tells us that God told him to go there and to tell them of the gospel that he was sharing with the Gentiles. Paul wanted to be sure that the gospel that he was preaching was the same as they were sharing with the Jews in Jerusalem. Paul understood that there was only one way to be saved and he wanted to make sure that he was not misleading people.

Galatians 2:3 & 4

"Yet not even Titus, who was with me, was compelled to be circumcised, even though he was a Greek. This matter arose because some false brothers had infiltrated our ranks to spy on the freedom we have in Christ Jesus and to make us slaves." NIV translation

There was a controversy going on in Jerusalem over following the Mosaic Law. Paul says that Titus, a Gentile, was not forced to be circumcised even though some men were trying to make believers slaves to the law again. He even says that the controversy was started by people that had not even truly accepted Jesus Christ. Without Christ, they were slaves to the law and wanted others to be as well. What Paul is saying about being a slave is the fact that, if you trust in the law instead of grace for salvation, then the standard is absolute perfection. That means that you would have to keep all of the law all of the time with no slip-ups and that made you a slave to the law where grace makes us free in Christ.