Make sure no one has registered yet the nickname you want. First go to Status window (the top left button with the ICQ flower symbol). Then you can simply type in the command line /NickServ info (where stands for the nick you want to check whether it's registered or not).
If the nickname isn't registered yet change your nick to the nick you want to register. You can do it type /nick (where (stands for the nick you would like to be using).
Now you should type /NickServ register (where stands for the password you want to set to protect this nick).
In order to enable you to keep your nickname, you will have the option to enter your email address. In order to do this, add your email address right after typing your password: /NickServ register
That's it. This nick should now be registered under your name. Make sure you don't forget its password.
For more help on nickname options try using /NickServ help.
