How do you make a normal song your ringtone?

I'm getting a new phone soon, and It's the LG Rumor Touch from virgin mobile! I was wondering how I can get a ringtone like Mine by Taylor Swift, or just any song that you hear on the radio, that's good quality sounding? I really don't want those manual ringtones.. haha. I would love good quality, not all crackling, and sounding like somone recorded it themselves! If you know of any websites, or downloads from Virgin Mobile, please leave a link below! No virus-websites either! Preferably a trusted website? Thanks! Oh, and If it can be free, that would be AWESOME! If not maybe around $1? (: Thanks!