I guess I'll make a quick tutorial for everyone who's not familiar with TS yet ^^
Firstly, you can connect to the server either using the Quick Connect function, which is the easier one, or the Connect function.
Just type in the IP, server password and the nickname you want to use for that.
The second method (and actually the better one if you use different servers, cause you can save all the information) is using Connect.
Here you rightclick on the left half of the menu (the white space) and choose Add Server. Name it as you like ^^
Seeing as how you're not yet registered when you login the first time, you have to type in the IP (Server Address), the nickname you want and the server password. Also, leave the Login Name and User Password blank and change it to Anonymous above that (otherwise you won't get the nick you want when you login, but Guest1 or something).
After I gave you rights to register (if I catch you on there xD), click Self -> Register with server and type in name and password you want.
(can't really do that since I'm already registered xD but you get the idea.)
After that, you can put that information in the Connect menu too and change it back to Registered =P
Oh, and you can still change your nick to whatever you like as long as the login information stays the same.
(note the different nick here)
I hope that makes things easier for you guys <3