Is there a possibility to set your own background Image.......I know how to change the colors in the Theme Editor......

You mean on your profile background or the forum as a whole?

There is no built in function to do this, no. You would need to apply your own CSS to do this

@dogbone

For user profile page background image change, this third-party app is pretty cool.

Furthermore, all apps from this IPS Dev is very cool 😎.

IPS App Zone

Advanced Profile Page

Transform your profiles into a space where creativity and self-expression thrive with Advanced Profile Page!Key Features:Custom Backgrounds: Let members personalize their profile with custom backgr...

Thank you, i try out this code, yepp i have some great apps from him.....