The author identified himself as James. This was probably James, the half-brother of Jesus was a leader in the early church and part of the Jerusalem council. The Apostle Paul also called him a "pillar" of the church.
In this letter, James encouraged believers who were suffering, telling them that God uses their suffering to help them become mature Christians. James also told them of the need for believers to do good deeds. He wrote much in this letter about how believers should live and treat one another. For example, he commanded them to treat one another fairly, to not fight with one another, and to use riches wisely.
James taught his readers by using many examples from nature such as in 1:6, 11 and 3:1-12. Also, many parts of this letter are similar to what Jesus wrote in the Sermon on the Mount (Mat 5-7).