Joomla: How to set the default template?

I would like to change the template in a Joomla website but when I install it I can't select it as default theme, for example like I c开发者_运维问答ould do in WordPress.

How can I activate the template?

I attach the screenshot of the backend:

screensoht of the backend http://img714.imageshack.us/img714/2283/schermata20110228a17540.png

Thanks

Goto Top Menu bar => Extensions => Template Manager.

Here select the template(from left side radio button) which you want to make default.

And click on the default(star) icon, on top-right side.

I solved the problem.

The problem was that I wasn't a super administrator but only an administrator so I hadn't the right to set the default template.