Right.
Deep breath ... and ...
Fit the trail inside the front of the gun shield. It hooks up and under, and the shield should be pretty much vertical. That bit is important.
The two flat square seats fit on either side of the shield at the front. The one with a hole in the front fits on the right. Each one has a 'U' shaped step that is attached to the front and leans outwards and downwards at about 45 degrees.
The gun sits in the cradle and the barrel is fed through the front of the shield.
The sight (small thin 'tube' with a block on both ends) fits on the left of the gun breech - you can see this in the photos.
Trail 'spike' (curvy handle) fits on the end of the trail (a-la photos).
Slide the crew seats under the breech into the channel. These look like a curved rod with a flat seat at each end, or thesame with the seats missing. Choose either ones with or without seats attatched - noting that the figures themselves have seats moulded onto their bums if if you are going to crew it.
There should be three little wheels.
Two are slightly bigger, and the other slightly smaller
.
The small wheel goes into the front of the right-hand fold down seat that sits on the front of the gun shield.
The two bigger ones are travese and elevation wheels - these fit in the holes on the breech and cradle (you can see one through the spokes of the wheels in the picture above).
Stick the wheels on.
Bingo!
I hope that this helps. Once youve got the big bits together then all of the small parts actually have holes or ledges etc. for mounting.