You can also get free ringtones emailed to you if that works better for you. Then do what you want with it from there (including putting it on...
Does your phone have bluetooth - if it does you can send files from your computer (via bluetooth) to the phone. You just have to sync the devices...
this site has free MP3 and AAC ringtones - i found some good stuff here: http://www.tonecrusher.com
Separate names with a comma.