Linking a server to a large network is very hard, and requires sponsorship from large ISPs or universities that can donate the bandwidth to run the server, due to the huge load that the servers will undergo.
Smaller servers could be hosted on shell accounts. These servers are not accepted by most networks due to their instability etc., but if you're running a server for a few friends then it's ok. This does cost money. Search Google for things like "shell accounts" or "IRCD processes. It does cost money.
An IRCd (Internet Relay Chat daemon) generally only works on non-Windows systems, i.e. FreeBSD, but
Unreal IRCd is one that works on Windows. WIRCd's (Windows Internet Relay Chat daemon) are basically IRCds that run on Windows. They are not as stable and generally considered not as good as IRCds. You can get them from
wircds.net .
Ask in the #Help channel or ask a network IRC Operator for information on how to link a server and what teams deal with the linking of servers and what websites to visit, etc etc.
Hope this helps
Regards,