First addon, need advice :)

[nilo]

Recently I decided to learn more about addon development so I thought about a simple ideia that would be handy and hopefully easy enough for a first experience, so after a couple days of research and tutorials I dont know how to aproach this. So my ideia is to add some kind of role indicator for tanks and healers only (either the tank/healer icon or even the letters T/H) next to each players name in a large group according to their role if they belong to one of these.
Would be great if someone could point me in the right direction.