Thanks to GODZSON for support concerning the fonts customisations!
Download the zip file on your computer. unzip. put the .teme file on your Diamond into the folder "/Internal Storage/Themes. (if it doesn't exist yet, create it)
Intall the "wallpapers" folder anywhere as you want on your Diamond. Those themes must be installed with TF3D config . Follow the developer's instructions.
To install on of the wallpapers, go to "Settings" tab on the tf3d and choose "wallpaper". The wallpaper only appear one the "Home" main screen of the TF3D.