If you are after a free image editor, The GIMP is free, but has a learning curve. I use it to edit my thumbnails.
Have you tried Fiverr? You can commission someone to make a logo for you, they could also sort banner art for you too.
looks like fiver might be the way to goDid some myself.
Ended up with a fiver one now![]()
I used inkscape (which is free) because you want logos in vector rather than raster format - that way you can blow it up as much as needed with no loss of resolution - very useful for when you want to print it on a hat or t-shirt for merchandise etc.