I'm new to using a sewing maching myself, when I did my bug net on my hammock the other day I used zig-zag stitch to add some kind of strength.
think I would be inclined to google/youtube a french seam there's another people use to do make the ridge seam in tarps but I don't know its name.
but I guess the basics of the seam you would require, would be like a folded/rolled hem then material opened out hem laid to one side and stitched flat.
I have thought of adding bug net to my tarp also but at the moment I'm unsure on how I want to use the tarp most.