Correct! —> OneMoreTime already provided you some examples.
This was your comment…
I have a number of boxes within a container and want to highlight a box when its clicked
And surely you generated all your stuff → as fixed boxes on your page, which is surely not the best way to go. You always should try to create and generate your site as much dynamic (flexible) as possible.
The more you programm your site in DYNAMIC-WAY → the more → INTERACTIVE it will be at the end.
Try to work more with REPEATERS and DATABASES.
You will understans very quickly, why this way is a much better way ten working with hard-coded codes or static programmed pages.