Say I create a page and it goes to be #9 for a search term with 2 million results. This page, can it help my SERP for the main page, index.html? So I wrote an article about geothermal heating, found that it's #9 for a result: will this help my main page www.spartansaving.com SERP?
Yes, every one way links will help you to boost ranking for your main site. But links must be relevant and from targeted keyword as a anchor text.
I am as it's one of my own websites pages. Say I get http://spartansaving.com/Geothermal_Energy_Heating_Investing.html listed as #9. Will that help boost my main page's SERP http://www.spartansaving.com?
It can if you set up the internal flow of page-strength correctly. If the page you suggest has many links pointed to it - link it to your index page with internal anchor based on one of the key phrases you are trying to rank for. Dylan
I do have a link to the home page from every site, it's concentrated in the top left with two links pointed to my index. But I understand what your saying.