Don't worry we're here to help you get up and running.
I suggest you factory restore your device and make sure you're running the latest version of XBMC (12.2).
Once this is done you will want to launch XBMC.
You will want to install fusion...
On the main XBMC menu where you see VIDEO - MUSIC - PROGRAMS -> SYSTEM etc.
On the bottom left hand corner of the screen there should be a small 'power button'. Scroll down using the remote and click on the 'power button' you should now have several options including power off and reboot.
You will want to highlight over the repo and first choose 'check for updates' followed by 'force refresh' once this is done you will want to wait about 1 minute and reboot your device.
Here is a guide on doing the force refresh for the Mash Up add-on: