In your profile settings there is a line for your sig. You are using it right now for your sig line about Model Traders Haven.
To add a pic to that line, first you need to host the pic at a hosting site. The add the url for the pic to your sig line like this
This will call the picture up every time. Please note --- remove the spaces between the g and ] I have added them for display purposes only .
Happy Modelling and God Bless
Robert