With the apostles preaching in full swing since the death of Christ, the church was growing so fast that the carnal nature of some began to surface and the murmurers began accusing the apostles of neglect. Now, the apostles instruct their brethren to pick out seven men, "full of the Holy Spirit and wisdom, whom we may appoint over this business," as it says in verse 3. Thus, we are introduced to Stephen, who is named first, and described as a man "full of faith and the Holy Spirit."
Now, since the death of Christ, indications are the growth of the church continued multiplying greatly, as it says in verse 7, so much so that even some of the priests began to be converted. Now, Stephen took his calling very seriously and went about full of faith and power, doing great wonders and signs among the people, and doing so, he drew the attention of a group called the Freedmen of the Synagogue.
This term freedmen is used only once here in the Bible and it is not totally certain who they actually were, or at least I could not find it. There are several ideas but they are just speculation and nothing concrete. Some believe they were Jews, some who had been enslaved by the Romans, and there are others who believe they are Hellenist Jews. There is another idea that this is quite possibly mentioned just to indicate where Paul's connection to this group came from, because it mentions Cicilia and Tarsus is a city of Cicilia.
Now, whoever they were, they do appear to be of the synagogue and began disputing with Stephen regarding what he was preaching, but they could not overcome the wisdom and the Spirit by which he spoke. This group seemed to be more vicious and vindictive as those who had plotted to kill Jesus as they began their plot to silence Stephen. Indications are that at least some of the same people were involved. They set up false witnesses to testify and even paid them to say that Stephen was speaking blasphemy. And we find that in verse 11, they purposely went about to incite the people, the elders, and the scribes against Stephen, so much so that they seized him and brought him before the council. They got someone else to do their dirty work, as we might say today.
The word council used in most English Bibles seems to indicate the Sanhedrin, which has 71 members which are presided over by the priest, and I think the same priest was still in office from the time of Christ being crucified. Now, the council consists of the two sects of the Pharisees and the Sadducees. These are the same people who plotted to kill Jesus and who were persecuting the apostles. And later on, they were the same ones that plotted to kill Paul, all because they were filled with jealousy, as it says back in Acts 5:17. They were once again trying to preserve their position in the synagogue as more and more people began to believe the true gospel.