jQuery AND jQuery-UI

Hello.
I am having problems to understand how to use jQuery and jQuery-UI at the same time.
I want do do something to pick out different things on the page and not only should this items change (using jQuery-UI-Selectable) but i also want to change other items on the page too (like with jQuery-fadeTo)
Sorry if this is a really dumb question, but I cannot find any answer.
Markus