Hi Becky, and welcome to Sitepoint if you haven't been welcomed already..
Yes, that's a logical step dividing up your page into 3 divs.
I would also create a wrapper div for the fixed width and centering of the layout.
Yep, you've got the right idea - Create another div within your main div with an id="nav"
Can I use a div id=nav and positioning attributes? Is that something I should use the float property on?
If you apply float: right and give it a width it will go over to the right and the text will flow around it.
Something like that would be my starting point. Remember to use semantic markup that means using list tags when you have a list of things - A heading tag for a heading etc.. You can completely control the style of these elements in the CSS.
<h3>Professional Certified Coach</h3>
<li>Products For Sale</li>
Hope it helps