enhancing sidebar/navigation

Hello, I’m a noob to wordpress and am learning as I go. I’m trying to the sidebar to reflect nested link under an main link. Here is what I like it to do:

home
about
interest
contact

when you click on ‘interest’ it should have link1 and link2. IE:

about
interest
– link1
– link2
contact

the nested links under interest should only display when ‘interest’ is click and disappear if another main link (ie about) is clicked.

I’ve read all the tutorials regarding editing sidebar and navigation php and have had no luck. I’ll appreciate if someone can tell me what script I need to use and where to insert them. Thanks!