Your doing it already.. your links in your signature.. you can also submit your site to social bookmarking sites and leave comments on related blogs that are dofollow.
dofollow simply refers to a link being followed when crawled by a bot. This helps create backlinks to your site. posting a link on a site with nofollow will not create a backlink to your site.
Here is a small post telling about backlinks and how can you get them http://www.dailytechnologytips.com/2008/05/backlink-definition-usage-and-tips.html Hope that helps. Dofollow links are those links which search engine crawlers are allowed to follow means they can crawl that link, on the other hand nofollow link will be simply ignored by search engine crawlers.
One great way to get good backlinks is to find related sites and offer to pay them a bit to link to you. Of course, Google frowns upon paid links, so you would not want to make this public knowledge! (And you certainly wouldn't want the link from their site to yours to look like an ad - then, Google may deduce it is a paid link.)
You can submit your pages and articles to social networks such as LotText, Propeller and digg. It is easy and helpful.