drive it up the ramp on tickover. Park it against the bulk head let the clutch out and stall the bike against bulk head. Leavi gear. Leave bike on side stand.
Strap bike loosely ,on stand side first, from a frame rail or something solid, not foot peg or subframe idealy, handel bar if nothing else available, to tie down point on floor. Make sure tie down is pointing in the strap direction or it will bend and the bike will work loose.
Then do non stand side and use the strap to pull the bike upright, do not strap onto a stand or it may bend, you need to compress the suspension onto the tyres, stand may go through the floor.
Tighten down evenly side to side until solid. If sitting in the bike loosens the straps its not tight enough.
Tie the brake lever as said. Turn off ignition and petrol tap if it has one.
All this assumes you dont have a slow puncture.
But those straps aint man enough, you need ratchet straps. Halfords do them.
May need to wrap frame rail or bike tie down point with a rag incase the strap marks.
When loading make sure the drive at the rear wheel doesn't push the ramp out when the front wheel is on the van, and that the belly doesn't catch on the top of the ramp.