I've just added 4x pics to illustrate our previous set-up ie Tarp, Tent and Trailer
1) We placed the floor down first. We have previously marked where the tent is located (eyelet holes for anchor pegs etc are in the floor already)
2) Then comes the Tarp (start at one corner then the next on the same side of the rigid beam)
3) Then comes the tent.
The tricky bit is leaving enough slack and "bringing in" the side pegs enough to allow for a ridge beam across the centre ie the extra height required. We always seemed to need "re-pegging" to get it right. But worth it in the end.
If you look close enough you'll see a candelabra on the table (never go camping with out it as SWMBO says it gives ambienece