Sorry Sicilianos I just figured out what YIM meant, can't help you, but for those of us with MSN Messenger here's what you do.
Open MSN Messenger, click Help,About, and see what version you have 4 or 5.
Then go to the MSNSkins site
and download the SKIN BACK file (upper right of the site) Save it somewhere on you computer. Close Messenger and double click the file to launch.
Then download the skin
,chose the right one for the version of Messenger you have, again save it to somewhere on your computer, close Messenger, double click it and your done.