Welcome to the forum!
It's a known problem for some people to have trouble finding all of the servers in the wq3 multiplayer menu. Make sure you are searching for 'full' & 'empty' servers on the internet. The game has to check over 1000 q3 servers so it can take a minute or two. Give it some time. You can also try
Monster Browser which works well for some players but can also take a minute or two to find the servers. Another thing you can try is a game launcher that will work from our
server website. Near the top of that page you will see icons for game launchers that will work there. Once you install one, you can just visit our server page, click on the server you want to play on, then click on the appropriate launcher icon. Personally, I use X-Fire. Let us know if you have any more questions.