There's two types of searches that can be made. The one up in the right corner is Google search which generally produces more relevant results.
If you want to make a specific search click the magnifying glass below it which will bring up the internal search engine. You can narrow it down to author, forum etc. Results are returned in chronological order so if you have an idea of when it was posted click ahead using the pagination. For example if I search for "test":
Search found 3393 matches • Page 1 of 227 • 1, 2, 3, 4, 5 ... 22
The "Page 1 of 227" is a link that will allow you to jump to any page you want. http://nepacrossroads.com/search.php