The member list, accessed via the 'Members' link at the top of each page, is basically a listing of all of the members that have registered on the board.
If you'd like to search for a particular member by name, you can type in the name of the member in the far left field. 'Begin With' will search for members beginning with the letters typed in the search, while 'Contain' will search for names containing the characters.
If you'd like to only search for members that have a photo in their profile, check the "Must have a photo" box. You can also narrow your search down to a user's gender and their minimum rating.
By clicking on the "Toggle More Options..." button, you can display more fields in order to search for members.
Home Page Contains: This field will search for the entered text within the contents of a user's home page fields.
Signature Contains: Similar to Home Page Contains, this will search the signatures of users instead.
Messengers: In this area, you can search for particular screen names for the dominant instant messaging clients.
Post & Date Ranges: This area will allow you to narrow down your search to particular posting and other date information, such as users that have joined after a certain date, or users that have more than a certain number of posts.
Just below the search area is a set of fields to sort your results. You can choose a particular group (or All Members) in the first field, then sort those by Name, Posts, Joined Date, or Rating (if enabled) in either Ascending (A-Z) or Descending (Z-A) order. The final field will control how many users are displayed per page.
At the bottom are the profile cards for members matching your search. These will display a basic summary of the user, as well as their photo if they have one. By clicking on the user's photo or name, you can choose to view their full profile, add them as a friend, send them a message, or find their posts.