Just wondering, do I need to have a registered version of mIRC (meaning I payed $20) to register a channel? If not, how would I go about doing this, I've done /msg chanserv register #xxxx but it says I must first authenticate with AuthServ.
Channel registration varies greatly from network to network. Try typing /msg authserv help or going to the network's help channel (try #help or checking the MOTD).
mIRC is just an IRC client, it has no control over what servers/networks can and cannot do.