You can buy backlinks at very cheap rate from sites like SEOclerks, listing dock etc.

create blog and forum posting

Back links are very important for any website ,because by back links search engine understand the importance of your website,also improve your page rank,keyword ranks.
For increase back links do:
- Blog commenting on high PR website
- Social bookmarking on quality sides
- Directory submission on high PR do follow website
- Article submission on top high PR website
- Blog submission on high PR website

try to post your web link in pr forum/blog/website