hii firends my site gets google top rank or "I am feeling lucky" with the keyword "armpit forum" whcih is a very valuable keyword I guess. But my pagerank is 0. can you guys suggest anything to improve that or how should I utilize the high key word ranking.
No one searches for "armpit forum" - I would suggest finding some keywords that people actually search for. http://tools.seobook.com/keyword-tools/seobook/index.php
To be honest armpit forum is not a valuable keyword at all. There is no search traffic for it. Use this free tool: http://freekeywords.wordtracker.com/ and try to find other keywords in your niche that actually get some traffic.
Do some keyword research, find the best keywords that will bring you real traffic and then SEO your site around those keywords, make good use of h1 tags and get backlinks with your keywords in them as anchor text.