There are a few ways to find trails:
Search Box: The "search for a trail or category" search box in the toolbar at the top of the page will search for entered text in trail articles and also in titles of the trails themselves. If you enter the precise name of an existing trail, you will be directed to the trail article. Otherwise, the search will find matches of text entered. The case of the entered text is ignored.
Map Of Trails: Click either the link "Map Of Trails" in the navigation area on the left hand of the page or go to http://clevertrail.com to access the map of all trails. Trails are clustered to reduce loading time, so zooming into the map (you can use the zoom control in the upper left, double-click the map, or click on a cluster) will show the trails within the clusters. Clicking on a trail will take you to its trail page where you can read the information about it.
You can filter trail maps with the filtering options in the lower right of the map. Change the criteria to narrow the selection of trails that are shown.
The option "Include Trails With Incomplete Data" limits or does not limit trails when the criteria selected is not filled in for a given trail (for example, if a trail doesn't have the Distance value for it, it will or will not show up with the checkbox).
Additionally, you can search the map to bring the view of a particular region closer. For example, in the search box labelled "search map for a location", entering "california" and then pressing enter will center the map on California and zoom it in appropriately. You will then see all of the trails and clusters of trails with their trailheads set in California.
Categories: You can search for categories, such as national parks and places (like "Yosemite National Park" or "California") in the Search Box. Once you find a category page you are interested in, you will find a trailmap just like the Map Of Trails on the homepage. This trailmap will only show trails that have been marked as being in the given category - you can then select trails just like you would on the homepage.