The Call to Diocesan Priesthood
There are many guides and supports to those who wish to discern a Call to Priesthood and Religious Life. Each Diocese and Religious Order have a person named as Vocation Director who assists and meets with those who wish to pursue a vocation.
In the case of diocesan priesthood, if one wishes to become a seminarian, one applies to a particular Diocese. If a diocese chooses to accept a candidate that person is then sent for a period of formation to a seminary.
The following sites give information on supports available for those discerning a vocation.