Easy peazy man. You should have a CD that came with your phone, or you can download it from the web(I would imagine). You're looking for a tool called "Mobile PhoneTools". I installed mine from the CD.
-Run it and it'll try and install your "modem" which is your phone.
-Then plug your phone into the USB cable (plug it in after you run the program)
-After a few seconds it loads and shows a piccy of your phone on screen.
-Hit the explorer button on the far right (the one about half way down I think)
-It opens a proggy where you can move videos, music and stuff across.
-Hit the music tab and then start copying MP3s over.
-Close it down and unplug your phone.
-Go to the menu, multimedia, sounds place. Navigate to your new sound. Hit the middle menu button. Hit apply as ringtone.
I currently have Aifwolf. I also have the "aids aids aids aids" finalle from Team America as my text message tone. Slightly embaressing if you're in a lift with someone, or, as happened to me a few months a go, walking past a load of people collecting money on national aids awareness day. "aid aids aids aids aids aids .. aids a a a a aids aids aids aids a a a a aids aids".
Hey, we all do stupid things.