deleting unnecessary files on V3

i am new at trying to hack my phone and am having a bit of trouble. i have a V3 Cingular razr. i am trying to get rid of the factory ringtones and themes and pretty much anything i don't need to free up some memory. i need to know what i can delete and how i can do it. i tried the p2kcommander program from this site, but have no idea how to use it. thanks for any help.