How to install themes in ubuntu 8.10 GNOME ??

Download a theme (.tar.gz format mostly). [Example Theme]
Go to System > Preferences > Appearance and drag-drop the file into it.
Upon successful message, press the Customize button in the same window and choose the installed theme from the list to apply.

C'mon, this one was too easy to figure out by self!

Thanks Qwerty..I didnt know it was so easy

I applied Mac OS X theme ..it doesnt change any icons ..only windows borders and colors

Icon themes are to be installed separately. Here are several.

hi every1

i did the above steps it does not want to install it tells me that the file i selected does not appear to be a valid theme!!

pls help

^^File might be corrupted