Put your M/SD or T/F Card in yor pc & open card.
open up the " _system_ " folder then open up the " themes " Folder
**If this folder does not exist, just create it.**
you will see 12 folders with the names Theme01 > Theme12.
copy your original ones to your pc as a back up.
copy and paste the ones you have just down loaded it should ask you to " confirm the file replacement " click yes
Thats pretty much it.
Once installed just press the "'*Select*'" at the main screen where you select the
'Games' - 'Music' - 'Moonshell'
then press 'A' and its done, repeat this until you have found the one you like