WordPress MU

Hi, I'm a new wordpress user and I'm trying to customize my site. Right now on my left side bar there is a heading called "Pages" that list all of my pages. How would I customize that. So that heading for example would be "Dogs" and then contain all my dog pages. and then I would like to create another section underneath with "Cats" and contain all of my cats pages. Is there a plugin to do this, or do I edit HTML?

Thanks for your help!

Create a page called dogs, then create sub-page under that. Or explore the category options.

Thanks, I understand that but perhaps it's not exactly what I want.
http://www.scfreak.org/

That is my site as of now. It's pretty bare, I'm planning to purchase a template and then upload my old content onto it.

I would like another heading in bold as "Pages" and have it a different word. For example have that "Pages" in bold say "Dogs" and then have another section where like archives are with "cats" in bold... If that makes sense. To split up my pages in sections.

Categories also wouldn't be what I want...It is hard to explain. I'd just like total customization to change all the words and split the page links up.. I'm sure there has to be a way to do it. Either plugin or editing html..

You're in the wrong forums. Go here wordpress.org

bustherh's suggestion is closest to what you want without doing manually.