A easy program to use is on your PC is the sound recorder in Accessories/Entertainment.. This will help you chop up you wav files, it's easy and helps your ringtones, alarms etc, to be short or as long as you like.. Well enjoy your tunes.
P.s.
don't compress the file to much cause they will sound horrible just make it atleast 15 to 20 seconds and under 8mb audio size 16 bit, channels 2(stereo) and 44khz.. Be Safe