In the rich text editor:
@Shineheart26
In a comment:
[Shineheart26](https://chowlings.com/user/Shineheart26)
For Names and Avatars:
In the rich text editor:
%Shineheart26
In a comment:
[![Shineheart26's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/Shineheart26) [Shineheart26](https://chowlings.com/user/Shineheart26)