Well, sort of simple. I guess I should have known from the start. The reason the image is sometimes put in sideways is because the image is too big and you need to resize it. You can do this quite easily in paint.
Open the image in paint. Click on 'home' next to file. Click 'resize'. Select resize by pixels. Set the horizontal to 1000. Then save the image. It will now display on steemit as want it to.
I am sure people know this already. But it might be helpful to newbies.
