Please help me figure out my Blogger background problems

I have a site that I'd like to experiment with backgrounds on and I can't figure out the answer to any of these questions. Google either provides irrelevant or unhelpful results. I'm not necessarily looking to do all three of these things at once, I just want to figure them out. I am using the Contempo Light theme. If there's HTML/CSS I need to edit, pls tell me.

1. How can I use a single image as a full background for a page, with no background color?

2. How can I make a background image stay in place? The "scroll with page" seems to do nothing.

3. How can I tile an image as a background? I have a 360 x 360 pic to be tiled, but whenever I select it as my background image, it's sized up and fits the entire background space. The tile options do nothing.