Registration of the Nickname is a IRC Network function. If the network supports registration they have a process to do it. I would suggest you look for a website associated with the network you are trying to register your nickname on. On that website should be an area for Network services, and in the services area, a help file for how to register for the network. Since there are many different networks, and as many different registration pricesses as there are networks (almost) this is the only logical way to resolve your issue unless you identify the network on which your trying to register your nick.
Hope this helps,
HorseC
