PageRank is Google's way of deciding a page's importance. It matters because it is one of the factors that determines a page's ranking in the search results in the way to increase the page rank likes the back link is the one of the best way to increase the page rank to your website
Well thanks for the link. Normally I don't bother about PR. I think it comes naturally. If you continue your SEO and maintain it consistently then PR will rise automatically.
There are so many methods to increase the Google PR - 1. Unique Content 2. Proper on page optimization 3. Quality back links :- Forum posting, directory submission, article submission, blog commenting, social bookmarking, theme based one way links. 4. User friendly Navigation 5. Create many pages of your site. 6. Domain age is another factor.