How do i set my music as a ringtone on iphone 4

Method 1: Using iTunes:

1. Make sure your ringtones are in m4r formats, then you can add ringtones to iTunes library and sync to iPhone directly.
2. If you find that the formats are not m4r, but in mp3 or other audio formats, then you need to import the audio file to iTunes library and trim it first. Save the trimmed audio file into AAC format, then substitute the AAC extension to m4r. And you can refollow the point 1 to import it as iPhone ringtone.

If you want to change the ringtone on your iPhone, the steps as below will help you to perform this task in an easy way.
1. Tap on "Settings" on the home screen of your iPhone. Then choose the option "Sounds & Haptics".
2. Tap on "Ringtone" in the section of Sounds and Vibration Patterns. Multiple ringtones can be found in the list and you also can see the current ringtone which is being used.
3. In this "Ringtone" screen, all ringtones on your iPhone can be seen here, you can select the ringtone you like whatever the default ringtone or the purchased ringtone or the custom ringtone.
4. You will see Alert Tones when sliding down the screen of your iPhone, Alert Tones are usually applicable to alarms or other notification, but they can also be applied to ringtones as well.
5. You can preview the ringtones that you have chosen, as the ringtone will play once you tap on it, then you can determine whether this ringtone suits your need.
6. Once you have selected the ringtone as default for iPhone, the checkmark beside the ringtone must exist and then you can go away from this screen, then tap on "Sounds & Haptics in the previous screen. Finally, your selected ringtone will be saved automatically.
After that, the ringtone you just set will play when you receive a call.

For more details, check: How to Add Ringtones to iPhone

Hi,
It's a very tricky method. Follow these step precisely, and you should have your own custom ringtone like I have.

Please rate this solution if it helps you.
1 Open iTunes.
2 Find the song that you want to make into a ringtone.
3 Listen to the song and find the part of it you want to use. The chorus may be a good place to start.
4 Write down the start and stop times of the clip.
5 Right-click the song and select "Get Info."
6 Click the "Options" tab.
7 Type in the start time of your ringtone in the text box next to "Start Time" in the minutes:seconds (i.e., x:xx) format.
8 Type in the end time of your ringtone in the text box next to "Stop Time." Make sure the ringtone is no more than 40 seconds long.
9 Click "OK."
10 Right-click your song again and select "Convert Selection to AAC." Wait for iTunes to convert your song. It will create a duplicate version.
11 Right-click the ringtone and select "Delete."
12 Click on the "Keep Files" button.
13 Find the file. It's usually in your User folder under "Music > iTunes > iTunes Music" and under the band's name. It will have an extension of m4a.
14 Replace the m4a extension of your ringtone with m4r. You can either double-click slowly to rename your file, or right-click and select "Get Info" on a Mac or "Rename" on a Windows PC.
15 Click "Use .m4r" or the PC equivalent when the system warns you that the change may affect the use of your file.
16 Double-click the ringtone file. ITunes will automatically add it to your ringtones folder in your iTunes Music Library.
17 Connect your iPhone and sync your ringtones.