newbie questions

hello all

installation went fine, at im really interested in getting starting customizing the grafic. Im new to all this scrip stuff though, and there are some things i hope someone can give me a little help with.
I have just chosen a layeddown theme and just want to do a few modifications to start with.
so here are the questions…
i want to put an image at the top of the page, but cant seem to find the template to edit it in.
When creating pages with subpages, is it possible to do so that you have to click on the pages for the subpages links to show beneeth?

regards
jan