You need the title Id for What Game You Are Using(should be the folder on your hdd that has your saves and dlc in it make not of this location too, as well as the .esp of the mod you want to install.
Back on your 360's hdd/usb(must be xtaf formatted) drive go to your The game your using directory and if this folder does not exist make it anyway:
and copy the LIVE file you just made into that folder.
Now if there are any other files that your mod consists of such as Meshes or Textures then you will have to copy them into the root of the 'Data' folder in The game your using for them to work as well, because of this I recommend that you install The game your using to a storage device besides DVD(usb or HDD is fine but HDD or usb formatted to XTAF is needed to store gamesaves and DLC/mods).
Thanks To SnipeStyle About Telling Me About Le Fluffie!