Here are the photos of how we did that. Took half a day for 2 guys and $50 worth of 2x4, 1x3 and 2x2
I got cheap tarp for $25 (20'x40') - big mistake. Mother nature needed a week to almost destroy it - i'm going to the boat every weekend to patch with tape. Get heavy duty tarp. I'll see another week and if this one still does not hold will get something like this:
Silver Poly Tarp Sold Individually
White Canvas Tarps
and this frame is though enough to cover with drywall
Hope this helps.