Customization Question

Hi;

Right now if I click on a category in my sidebar, the latest post in that category is recalled in the center of the blog.

Instead, I would like a list of posts in that category to be recalled. If the user clicks on one of those links the list will be replaced with that post, with a navigation link back to the list.

My questions are:

1. What function do I use and where do I call it to get
a category link to pull up a list of messages in that
category?

2. How can I modify the navigation links to go back to
his list?

Thanks for any information

Steve