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