Background in wordpress

Hello

I have a wordpress theme and all set up.

Just need help getting the background image right. I have the image just need help putting it in the theme, There is a background uploader.

I just cant get it set right.

There a tree and sun on the left and a farm house on the right and I want them on each side off the site.

I just am unsure off the right css to do this.

This should be a very easy job so this is why a low few

Thanks