There are two options.
You can go to University(preferably Catholic) get a degree in Philosophy, with a minor in Theology. Then you would go into Major Seminary. If you went to a Catholic Seminary with suitable formation, it would be 5 more years before being Ordained. If you went to a regular University, you would need more Philosophy and Formation, and it could be more like 7 years in Major Seminary
Second option is you can go straight to Minor Seminary. The difference here is it will be all male, all considering Priesthood. It really doesnt make the time any shorter, still 9 years start to finish, but it would give you a better idea of Seminary.
The choice pretty much boils down to what kind of experience you want after high school. I personally am choosing to go to Franciscan University of Steubenville(shameless plug) becuase they have an awesome Pre-Theologate program that will ready me for Seminary, while I will still get to interact with a larger group of people.