Discernment means hearing the call and trying to figure out where God might be calling you to serve him. This is not something that happens quickly; it is a continual process of growth and listening to God.
First and foremost, discernment occurs in prayer. Often Jesus himself took time away from the busyness of his ministry to pray. In fact, his public ministry began with forty days of silence in the wilderness. When we pray we must silence our hearts and minds and listen to what God is saying to us and where he wants to lead us.
Discernment takes place primarily in the individual heart, but it also involves consulting with other people, especially other people in the Church. It is good to take advice from family, friends and clergy, who can help you make an informed decision. Discernment begins with an authentic Christian life, lived out in the Church.