If you're looking for someone, you might be able to find them, but, to be honest, the odds are not good.
In order to find a specific person that uses IRC (which is short for Internet Relay Chat), you're going to need to know what nick they use minimum. It will help reduce the odds of you getting the wrong person if you also know what network(s) and/or channel(s) that they chat on.
If you can supply that information we might be able to be of further assistance.
Please note that there are thousands of networks and some of them have hundreds or thousands of channels, each of which may have hundreds of users.