How to send a private message in IRC chat
This all depends on the IRC client you are using to access chat, and what's allowed. However, using one of the below methods should allow you to send a private message to someone with most IRC chat clients.
Note: Before sending someone a private message it is good etiquette to first ask that user for permission. Also, if that user is ignoring all private messages it will be ignored.
Double-click on username
Double-click on the username. If supported, a private chat with that user should appear.
Query or msg user
Using the /query or /msg commands also open a private chat with that user. Below are examples of how these commands are used. In both of these examples, we are sending a private message to the user with the name hope and the message hello. If you just want to open a blank chat the message can also be left out.
/query hope hello
/msg hope hello
Tip: Some clients also allow users to shortcut /m instead of the /msg command to privately send messages.