Drop down Menus?

Howdy. I’m running .72 on a test blog but am fine with this version as I’ve got it generally looking the way I want and working right. I want to add a drop down menus for displaying large lists of links such as archives, blogroll, etc. Does anyone know what code I should add to make a drop down menu? I’m really at the beginning of learning to style but I do learn quickly. I’m not wanting to mess things up so I’d really like advice before I stick the code in. Also would it need to be in the .css sheet or on the template?