How do you make an IRC bot

Depends. One I used was "Supybot", written in Python. You can also write one yourself, if you know a programming language, such as Python, Ruby, or C++. Configure it to run on the server and you're done!
Answer You configure a bot to run on a server, and give it a port number, and then connect. One you might want to try is Supybot or YourBot, both can be found on the internet for free. It should give you instructions on how to run it on the network, usually, running IRC Bots works best on *nix best operating systems.