Adding small pictures to your signature?

Simulacron

L-3: Simulated Member
aa
Feb 17, 2016
313
326
So I was working on my signature and was wondering if I could add pictures to it. I saw some people doing this, but I can't find an option to upload or link pictures. Is there some possibility to do so, or are there any restrictions in your signature if you aren't donator or veteran or something like this?