What you will need is:
-Horizon
-Flash Drive
1. Move you profile to your usb
2. Open modio and find your profile
3. Extract your profile to the desktop
4. Open Horizon and find your profile
5. Select avatar editor
6. Select the what you want
7. Save your profile
8. Open your profile in modio and Rehash and resign
9. Put your profile on to your usb and plug it in your xbox
10. Move your profile back to you HDD
11. Congratulations you have successfully Modded your avatar