Ima presently working on my website seo, some people saying div tags are very use useful to increase the seo rankings, how can it possible, it is true? How much useful div tags for SEO ?

As far as I know a web site designer is better off putting his/her energy into making sure he's/she's writing quality crawlable code and adding good content to the site than to worrying about placement/usage of divs. From everything I've read, div tags have very little impact on SEO. Yeah you'll find SEO experts that claim otherwise... but if you look long enough you'll find an SEO expert to claim just about anything. :)

Vasily