there's a variety of different apps, unfortunately none of which i know much about, most afaic use java. just as an example though there are some which are only a "room" on your server people must login through your website, others that are basically web-based thingys (technical term) to connect to an IRC chatroom - where people can join using any irc client such as mirc. the latter is probably "best" if you want people in it all day, but also is most open to the world and you'll have least control over (since the room will be hosted elsewhere and you'll probably need people in there most of the time in order to keep the controlling bot (like Q or L on quakenet) which will hold the channel for you and give you ops (Operator, i.e control) when you rejoin etc.
not a terribly useful post but gives an indication of options available to you 😱