Hello Alex,
The basics of changing your name are:
1. Fill out an application at the county courthouse for legal name change (look up where the courthouse is in the phone book, or online). There will be a small fee. You probably need to show your picture ID and maybe birth certificate.
2. Wait for them to approve the name change; sometimes, as here in WA, you have to appear before a judge at a given time and date and swear that it is you, etc.
3. Change all the other stuff that has your name on it like driver's license, credit cards, SS# etc. They will require a copy (or sometimes an original, so be sure you get extras at the courthouse) of the name change court order. It takes time to do this part, but you have time...
That's it. Try googling Penn name change process, or just go to the courthouse and find the name change counter.
Hope that helps.
Ruby