What is Chanserv?
Chanserv is a service that can keep your channels yours, keep topics, auto OP your OPs, and much more.
How Do I Use Chanserv?
Assuming you've joined the channel you want to own, and your nick is register simply type /msg Chanserv register #chan pass Short Descripton. (You can also type /cs instead of /msg Chanserv.) After that type /msg Chanserv help to see what other things you can setup.