Backlinks are huge in SEO. Google will rank you site as more important if it thinks that other sites are linking to yours because they think it is important. Think of it like a popularity contest. The more sites that link to yours the more popular your site is. Google will take notice and rank you higher in the SERPS. Keep in mind that you will get penalized by Google if you have too many back links at once. You need to maintain a steady flow of increasing backlinks overtime. A spike might raise some flags that you are blackhatting your way to get quick traffic. Do a search for “do follow” blogs and forums and post in them, but do it respectfully as you don’t want to piss anyone off in the forums. Also, what you were talking about earlier is call “link exchanging”. You are exchanging links with someone inorder to get a link back to your website. I stay away from this unless I feel a site is relevant and helpfull to me as well as others. I don’t ever downgrade the quality of my site’s reputaion just for one link. Try loading your webpage up with a few keywords, but make the content make sense. Don’t repeat random keywords because who wants to read that when they go to your site anyways? Traffic doesn’t mean squat unless it is targeted. So, target the searchengines to have its spiders crawl your site and look for the keywords you have placed.
You can get backlinks by white hat or black hat. Black hat can get you banned so be careful. White hat is sllloooowwwww as hell, but is the best way to maintain quality traffic.
Google a few of the subjects I talked about and you should be able to find more about these subjects by doing a simple search and reading up.
Hope that helps! Good luck!