Connecting to a server as a client is quite straightforward. Before doing anything it's a good idea to make sure your player name and color are what you want them to be. You can use the commands “setname” and “setcolor” even when off-line.
Notice that you can use your player number as a color if you do “setcolor 4” (both Doom and Heretic have four player colors: 0-3).
Hexen has eight colors, so you'll need to use “setcolor 8”. This means your color will be chosen automatically following the same logic as in the original Doom, Heretic and Hexen.
Set the protocol's configuration variables, for example “net-ip-address” and “net-ip-port” with the TCP/IP protocol. TCP/IP notes: the port should be zero if you're not behind a firewall, or some specific port of your choice (you'll need to open it) if you are behind a firewall. You can't use the same port number as the server, neither can you use the master server's port number 10123.
Initialize the protocol with the “net init (service)” command.
Issue the command “net search” as many times as it takes to see the server you're looking for (usually two times).
“net connect (server number)” will connect you to the server.
“net disconnect” will disconnect you.