i purchased a ringtone and i cant get it on my iphone 4

Morning vdquack1,

Thanks for using Apple Support Communities.

Using the iTunes Store for iPhone, iPad, and iPod touch

http://support.apple.com/kb/HT1491

Tones

You cannot purchase ringtones and alert tones from your computer, but you can purchase them using your iOS device with iOS 5 or later. You can purchase tones on iPad, iPhone (3GS or later), and iPod touch (4th generation or later).

To locate tones in iTunes on an iOS device:

1. Tap the iTunes app.
2. Tap Tones. If Tones is not visible, tap More > Tones.
3. Browse for tones. Once you purchase a tone, a dialog is displayed. The dialog gives you an option to set your new tone as your default tone or assign it to a Contact. If you don't want to do anything with the tone just yet, simply tap Done.
   
4. Tones purchased using your iOS device are synced to your iTunes library when you connect your device to your computer. On an iPod touch or iPhone, you can find tones in Settings > Sounds. On an iPad, you can find tones in Settings > General > Sounds.

Hope this helps,

Mario