Add graphic to username via plugin

[eviljoker7075]

Hi,

I would like to add an icon next to users in a specific usergroup. I know I could do this by editing the template, but I would rather do it via a plugin to avoid hassle when upgrading the template.

But I've never created a plugin before... Can anyone point me in the right direction, or even tell me if this is the best way to go about adding the feature?

Cheers