Static pages and blog pages

Hello,

I’m having trouble getting my head around some wordpress stuff particularly how I can stucture my pages. I have built my own theme. What I need to do is have a home page (this works fine with index.php)with a navigation which links to some static pages (how it works, about us ect) and the main page of the blog (I have blog.php as a template for this). I want this to display the excerpts of my posts and also link to my categories. I have got it linking to the different categories but can’t seem to get it to display the excerpts from posts unless I make it my index.php. I’m struggling, please help.

Thanks