Take a group chat member as an example. The other person is not your good friend. If you want to send a message to the other party, you can find the list where the other party is and go to the home page.
Then click the "Send Message" position in the lower right corner. Of course, you can also choose "Add Friends" in the lower left corner.
After entering the chat interface, edit the content in the chat box, and finally select Send.
There is another situation:
The other party is not a group chat member. In this case, if you want to send a message to the other party, you need to know the QQ account of the other party to find it. After finding it, go to the other party's homepage and repeat the above steps.