How to Change the Text Messaging Background on an iPhone

Jailbreaking Your iPhone
1. Launch your Internet browser on your iPhone and go to Jailbreakme.com.
2. Slide the 'Jailbreak' button at the bottom of the website. It will be labeled 'Slide to jailbreak.' Cydia will be installed during the jailbreak process.
3. Tap 'OK' after the installation of Cydia and the jailbreak process is complete.
Changing Your SMS Background
4. Tap 'Cydia' on your iPhone.
5. Tap 'Search,' then type 'SMS/Desktop Background.' Tap 'Install.' Tap 'Confirm' to allow the app to install.
6. Tap 'Settings,' then 'Wallpaper.'
7. Select the wallpaper you want to use.
8. Tap the 'i' icon found on the upper left side of the photo you've selected. This will change your SMS background to the wallpaper you've selected.