Default How to install themes (not from MIUI Themes store).....

Hi there....
i dont know that MIUI thread is suitable in this forum or not....but i need help guyz
yesterday i was installed MIUI v4 for Desire Z....and everything is ok....but i need to install a theme on it...
so, how to install a theme on MIUI v4 ? i cant find any way to do it help plz