https://youtu.be/OwzZTeAE3yc

have a look at this for basic tarp tension.

for the hex tarp its a bit more difficult to get it just right as you have an extra two chords. in the jungle i use two bungees, one at either end. round the tree, done. that way if the tarp stretches the bungees take up the slack.

use the ray meers ridege line quick release knot to get the tension you want on the corners and you should be good to go.