Can you provide link to "facebook jQuery". This will facilitate the solution of the problem.

There are a number of ways to inject jquery into your dnn sites.
One of the simplest is the Injector module that Will Stroll developed http://wnsinj.codeplex.com/releases/v...
It basically lets you inject anything u like into the html header section of a page.

The other cool option is the dnn widget system - there is heaps of info on this system here http://www.kalyani.com/2009/12/dotnet...

And for the best collection of free widgets for dnn - which are basically jquery elements wrap inside a html markup system - have a look at 
http://dnnwidgets.com/

Basically widgets allow the best of jquery without the potential dangers that allowing end user admins the ability to stuff bad script into what was previously a working site bring.