Your site must offer something to visitors that they will want or need, in essence, a reason for visitors to go there. This could be as simple as funny cat pictures for laughs to elaborate white papers about online security. Any route you go, there are sites on the web to help you get your stuff out there and in turn, promote your site.
Basic examples include:
Slide Share (presentations)
GigaSize (files in general)
With a little research, you can find a place to share what you have to offer.