Get links with your keyword in the anchor text (the clickable part of the link).
There are different ways to get links:
1. Write a press release about your web site. Use Google search to find sites to submit your press release to.
2. Find sites who write about your subject and ask them if they accept article contributions.
3. Submit your site to directories (it is easy and it still works).
Think of your own ways to build links. There are many ways to do so though most of them require work.