You can use organic traffic from the search engines, advertising as in ppc, or you can use the social media. Pay per click (ppc) can be very expensive if you don't know what you are doing and the traffic stops when you stop advertising. ppc classroom is one of the best learning sites, but is currently closed for new members
Getting traffic through search engine optimization is very competitive these days, but if you can make it to page one on Google you will get a lot of targeted traffic. A website that offers great software, but also provides very valuable content is http://automarker.net/seoelite.
The way of the future to get traffic to your website is social media. If you know how to use twitter, facebook, social bookmarking etc. you will get a lot of traffic to your site. Not a lot of people understand yet how to make it work for you. The only place I have found so far where you can get good trustworthy informaton is http://eventslisted.com/Social-Media-Books/ They organize free webinars where you can ask questions and discuss ways to drive traffic to your website. The page is a little different from most. You can sign up by clicking the link "buy a ticket" but it is free to attend the webinars.
