Creating Icons for Subjects - How to do it?

[puma]

  I've noticed that on some threads, the icons (displayed to the left of the thread name) will sometimes have something added to them.  For example, in the anything but piano board on pocorina's tuberculosis is forcing me to leave thread, there is a sad face attached to the left of the thread name.  Sometimes I see a balloon box, too.  How can we add these?  Is this something only the administators can do?

[mikeyg]

Right below the subject name line, there is a a drop down menu called "message icon"  open it and select. 

[puma]

   Awesome, I did not know that.  Thanks

[mikeyg]

Glad to see someone appreciates me somewhat.