Rather than edit and potentially messing up the previous post. 😐
What’s hard to see in that shot is that there’s a very thin line going from the tarp to the handlebars. It’s simply looped on the top part at the grip, simple tension is holding it there.
Unless there’s a strong wind you don’t really need the sides of the tarp to touch the ground, any rain/drizzle will just drop off the edges. This is one advantage of a tarp: you can choose the amount of ventilation to adjust for temperature/condensation. So if it’s a warm night with a breeze keep the sides up and the breeze will cool you down a bit. Conversely if it’s cool you can set the tarp with the windward side to the ground to stop draughts and the leeward side raised to give a bit more room. If In the photo if I wanted the tarp to be lower then I’d move the pole further away from the tarp.
As with anything you need to have a few goes at setting a tarp up. If you do a search you’ll find people who “know 27 different ways to pitch a tarp”. All well and good but in practice you’ll only use one or two so learn those well. I use the “dropped- A” for smaller tarps like the Rig3.5 as it gives the best compromise (a common word when considering tarps and pitching them) between space and protection. With the Rig7 I use the 2-pole mid (see this page for that ) which is almost a tent.
Some people use linelocks on the adjustment lines but I use Midshipman’s Hitches – doesn’t rely on anything other than the line itself, and you can’t lose/break the bit of plastic. Again worth learning how to tie whichever knots/hitches you might need, probably Bowline, Midshipman’s hitch and trucker’s hitch are enough.