In the animation the red line is the grey one in the picture I posted up and the blue "loopy" one is attached to the fly.
When it's tied to your tarp hold the turns of the pink loopy part and pull the grey line through the prussic to tighten the tarp.
The peg end of the guy just needs a fixed loop tied in.
chris n wrote:Learn to tie a tautline hitch at the peg end of the guy line and a bowline or figure 8 loop at the tarp end. Think of all the weight you can save.
Only tried it out on one corner of my tarp and took a spare in case it didn't work but I'm pleased to say it held firm.
Zero flapage.
Didn't you have snow?