So the premise is this:
John Carter is a vet of the Civil War. With only a handful of useless Confederacy currency in his pocket, he decides to go prospecting for gold in Arizona. He and his buddy strike it rich but someone has to go and get supplies and more men for the dig. On the way they run into trouble with some Indians. While hiding out in a cave, he somehow gets transported to Mars.
While on Mars he comes across a couple of different Martian races. The first group are large, war-like, and green. Think of the sterio-typical green martian and this is where it comes from.
They are at war with another group who look more like humans...except they are skin is bright red. And the green Martians have just captured a beautiful red Martian lady...the princess of a tribe of red Martians.
So of course there's the trouble John Carter gets into and out of, the little love story between the princess and John Carter, and of course a battle or two. It's definitely something a young adult could enjoy.
It was a quick and easy read and thoroughly enjoyable. I read through the library's e-book section but I found a ton of fun covers online.
These first two look more ancient Egyptian/Roman or something:
And I love the depictions of the green Martians in these: