My site, which has 7 pages in one month old. I´ve submitted URL to several web directories. I would like to know why Google indexed just the main page not the others?
It's just the way it goes desperado. If your site is crawlable, it just takes time. Your site is still very young.
Submit a sitemap to Google and make sure that your site is well inner-linked so google can easily find all pages. Make sure you change the meta description / keywords depending on the page or your pages may turn up in the "obmitted" part.
I solved the problem of same meta description on all pages with word press plugin "Head META Description" http://guff.szub.net/2005/09/01/head-meta-description/