How to change my ringtone to one of the songs in my music app on an iPhone 4?

How do I change my ringtone to one of the songs in my music app on an iPhone 4?

Jailbreak your phone and download a program called "Anyring" in cydia. Put the song you like to set as a ringtone in your music then all the song will appear in Anyring app. Then choosing and enjoy.

You DO NOT need to jailbreak the phone there are Apps that will do it for you or small programs that do it on the computer and get it in the correct folder when you sync next. A quick search on Google will get you multiple programs and apps.

Before loading down more apps, programmes whatever which all take phone memory try this.

Open phone tool box find ring tones.
Choose change ring tone which will open file containing ring tones that came with phone.
Scroll through and look for option that says 'all music and tones', select this and it will open All music files on your phone.
Scroll through until you find the track you want and select.

If this does not work try try this.

Open music files find track you want.
Scroll down to highlight then press options button.
Look for 'use as' option select this then select ring tone.
Save and job done.

I currently use a BB Curve, still use an ordinary mobile also (various makes) and have found that options like this are generally the same so it is worth trying before anything else.