This is actually done a long time ago (like sometime in 2011) but I never uploaded it here...
DISCLAIMER: This really isn't much of a tutorial but more of how I go about doing backgrounds specifically in SAI.
I might make a new one sometime in the near future a long with a coloring walkthrough on how I color. ( ̄▽ ̄)
I feel like I should share my knowledge and observations I've learned since that's how I learned to CG when I first started by reading other people's tutorial and and looking at their art.
Feel free to ask questions, I'll try to answer them the best I can.