Hi ms.gentry,
Thanks for using Apple Support Communities.
Using iTunes, you need to "Get Info" on the ringtones you want. Once the window opens, select "options" From there, you can change the type of media from music to ringtone. Remeber, the ringtones need to be in the .m4r format to appear as a ringtone on your iPhone. mp3 may work, but m4r is preferred by Apple.
Sync to your Phone, and enjoy your ringtones!
Ciao,
-Marcus