1. Here's a tip
It took me a few tries to use this tool successfully. With a new chain, and the adjusters fully loose, I coudn't seem to get it straight without making the chain too tight. I eventually realized that tension was needed to keep the axle tight against the adjusters. So, either tighten the chain temporarily, or wedge something in the rear sprocket to keep the axle tight against the adjusters. Once you've set the alignment, you can count turns to adjust your chain tension. Perhaps some better instructions would be useful with this tool.