1) Before you do anything, pray a lot about it, to make sure that is your vocation. 2) Then, decide which order interests you the most. 3) Ask at your parish, or ask any priest, monk, friar, or nun...
If you don't have a particular order already in mind, talk with your pastor at church, or contact the diocesan offices. They will be happy to give you some guidance about how to explore possibilities...