Hi, new and need help with heading and picture.....

Hi I am new to this forum, and hope you can help. I am not a developer, I tend to fiddle and elarn as I go along, but I'm having problems with understand how Atahualpa works, its a bit over my head, but I would like to be able to pick things up, if somebody can help.

I want to remove the picture in the heading, and add one of my own. how do I do that, and what size should it be.

Can somebody help please?

Thank you.

droopal