Contact the professor to see if you can get a position working in their labs. When e-mailing professors, remember that enthusiasm and interest in their area count for a lot. In the email, include
a) Why you are interested in working in their labs. Cite the web page, how it relates to your interest, etc.
b) Why you are a good candidate - List relevant classes, your major, resume highlights "As you can see from my resume.... " sentences work well.
c) Your resume, as an attachment.
d) Whether you are interested in a paid position or academic credit, and whether you're willing to consider a volunteer position.
e) Your availability to meet with them in the near future to discuss the position.