You should shorten your selection to around 30-45 secs. If you are on a PC you need something like Audacity (I think) to create a shortened recording. When done change the .mp3 suffix to .m4r, open iTunes, and import the track. If you are on a mac use Garageband to shorten the track and EXPORT to iTunes. Synch you iphone and set the Ringtone section to Either all ringtones or selected ringtones. Your ringtone list should be displayed if you have imported them correctly.