Yes, although its not very well written, i'll try and explain better, lets use the diagram for reference.
1/ To start with place your 6mm packers in the bottom hinge corner as per C and D in the picture, forming an 'L', you will have to silicone the vertical one in place to stop it falling down
2/ Place the DGU or pvc panel in the door on top of the packers, you will note it leans over to the right
3/ Get a glazing shovel and up in the top right corner push it in between the DGU or panel and the pvc, lever it over and put a 6mm packer 'B' in the gap, a blob of silicone underneath it will stop it falling to the bottom, this more or less should see the panel vertically level and equally spaced side to side, if not then thinner packers can be used for fine adjustments.
4/ Now comes the clever part and the last packer, using your glazing shovel push it in the gap on top of the panel, lever up on it and you make that gap bigger, lever it up till the diagonal weld on the door runs in-line with the weld on the door frame, now push enough packers in the gap 'A' so when you release the pressure on the glazing shovel the door doesn't drop.
5/ I find it best if you put the top packers in 90 degrees to the door so they poke out until you get the right amount in, try the door, make sure it locks and doesnt catch the bottom then fold/twist the packers in so they sit flat on the panel.
As for other packers elsewhere i would take up the gap over on the top left vertical, this stops the panel being pushed over when a burglar crow bars your door open, as well as that put packers level where the hooks or roller cams are, this will stop the pvc bending enough for the locks to disengage, more so roller cams.
This is the best way i can describe toeing and heeling, as i said earlier its a bit like trying to explain the offside rule to someone who doesnt play football. It would be interesting to know the thoughts of experience fitters as to whether i explained it well, its only been my trade for the last 20 years