If you are talking about skype ring tones, any monaural wav file less than
20 seconds long will do. You go to the tools menu, options, sounds and hit
the load ringtones button. Then, give it the path to the new tone, and hit
the open button. Now, in the tones list, select your new tone, then shift
tab back to the list box where you can select the item you want to
customize and make sure that the ringtones label is selected and you will
have it, hit the save button and you're good to go.