There are two ways to connect to these servers,
The first one is to add the hub. To do this you click 'Add server' and for the ip type '_ _.mcgamer.net'
The blanks represent the region you are from, if you are from US you will do us.mcgamer.net if you are from EU you will replace the US with EU.
Same goes for AU, CA, and AS.
The second way is to go to this website and click on servers, and select which region, (US, Europe, Australia, Canada, or Asia.) then look for games in the lobby stage (they will be green) and copy the ip of one that is not full (less than 24 players)
Next, open up Minecraft and go into the multiplayer section, press Direct Connect and press Ctrl + V (I think)
And then press 'done' (or whatever the button under the ip section says)