How to change theme in vista...?

I have windows vista ultimate OS and i want to change theme in vista which i have download from web....

I have theme (e.g Axenic_for_Vista_1_2_by_Austin8159 ) in that folder a file named Axenic.msstyles when i save all the theme file in windows theme folder and try to open that file, that file can't open and only ';appearance setting'; dialog box open.........

Now tell me is that any theme patcher from wich i can patch my theme file and could run any theme made for vista....Please give me the web address from where i can download theme patcher........How to change theme in vista...?
Right-click on your desktop and choose ';Personalize';. Then choose the theme option from the list. Another window will open and you choose the drop-down menu and go to browse. Then just browse to where you have the theme you want if it's not showing on the list already.How to change theme in vista...?
if you have the installation file directly install it... or else go to the themes menu and browse and select the theme file with the extention .thm.