Sorry I rushed earlier in my explanation. I just wanted to echo the advice everyone has given you. I would talk to your parish priest or a priest whom you get along with. Then go to the Vocations Director, ask if they know his number, and talk to him about it. You don’t want to rush into things but you should ask him who he would advise you to see about spiritual direction, ask for more than one name, so you can start your journey on solid ground.
You will need to have at least two years of philosophy to enter seminary as ByzCath wrote. There are schools that offer philosophy degrees but ask your Vocations Director what he would like you do first. If you are interested in teaching they may wish you to get a teaching degree first or if you have a passion besides the priesthood they will want you to look into that first to make sure you are not rushing and to see if you are truly called.
God bless you in your journey, I think asking on this forum is a great first step. Eventually you will need to ask your parents but I didn’t ask them about it before I talked to my parish priest. I wanted to get more info and I wanted to pray more before I told them. Then I told my dad and eventually I told my mom. They are so supportive.
Jeff