hi, i know that you must built more backlink if you want your site to get more higher PR. but the question is which sites provide free exchange link?
Link exchange is reciprocal link. It's better you find a one way link. It gives more reputation to your PR.
You can exchange links in the "link exchange forum in buy sell or trade forum.There's always threads for link exchanges.Make sure you put back links in a site that is in the same niche as your's
Usually exchange link is free. I post your link on my site, you post my link on your site. It's reciprocal, a mutual agreement without charging money. Probably you're nterested in free one-way-links, that means your link is posted on a site wthout your obligation to reciprocate. Well, you can have this type of backlinks posting in link and/or article directories, posting in dofollow forums (if your signature contains a link), posting comments in dofollow blogs.
if you want to exchange links for free, you should email website owners of your niche related sites and ask them for a linkexchange
All good sites exchange links with just reciprocal or they charge some thing for it ... because nothing is free on this world but you also can search some free directories over here those don't want reciprocal ...