Does it metter where to put a link to the site's main page?

Ok, so your question is reasonably unclear. However I think I have the jist, if not just ignore.
Basically, for SEO purposes, if you can get your link on the main index page that is great. That is why most reciprical link pages state your recipricated link must be on your index. (homepage).
For example if you are looking at the page rank of any website the pr is gonna be alot higher on the index page. Problem is that generally speaking you are not gonna get on the homepage of a high pr site. If you advertise with a site or if you leave a latest comment then it is likely to be posted over all of the pages.
With this in mind simple answer is yes, but dont get caught up in trying to hard to do it. Just get into the flow of a nice natural seo campaign and the results will follow. Do a few forum posts, a few blog posts, some directories, maybe make your own updatable blog site, maybe a few reciprical links and you'll be no.1 in no time. Just dont lean too heavy on one type of link. Hope that helps.

yeah it matters. I heard that Google give priority to the top left ads and then the top banner and then others. That clear describes the link positions also matters.
thanks

This sounds funny to me and i am not sure if that's true, but i heard that links in footer are not much of a value to google robots and PR.... So... Maybe, maybe not...

Much better for what? For seo? Or for people notice? The fact is that the link vusually at the top. BUT in code in the middle-end