A simple theme.

Hi!
I am installing wordpress for my granddaughter. I need a theme. I’m either going to have to find a free one or make my own. just a single column would be fine, with a rounded corner panel at the top(customizable by me) where I could put her log(a png or gif) I would also like to change the color of the entire page or at least the part where the panel rests. I need to where to find a theme like this or instructions on making my own. Any help would be greatly appreciated.
Thanks,
Paul