I see that loads of people have pictures above their names. How do I get one there? Or am I just being really stupid?

User Cp at the top, then edit options and avatar will be down at the bottom.

Thanks, I just tried that but it told me the picture was too big. It sounds stupid but how can I save it as smaller?

Open it in Paint, Tools, Strech/Skew, and enter for both Vertical and Horizontal 50. Save it. Try it. If it is still too big, do it again.