http://www.collegeboard.com/
Hopefully you have already visited a couple of colleges to get an idea of what type of school your child would like the best (large/small, urban/rural). Remember you should have all your applications in by Thanksgiving. Some may need to be in sooner. Most schools these days accept the Common Application which can be found at:
http://www.commonapp.org
If you have a 10th grader (I have one of those as well) they can go on the College Board site to pick some schools to visit over the summer.
A book we found helpful was: