This is , I hope, I clearer picture of what's in the box
I don't have a drop checker yet, the shop I bought it from had run out of stock so I am now searching for a LFS that has stock available
So do I put everything together before applying the solenoid to the cylinder
Plus there are no instructions as to which parts should be put together first, don't want the co2escaping if I set it up the incorrect way
Shouldn't matter if the dial on the cylinder head is closed, but it won't hurt to do it last. Make sure the pipes are on properly (a bit of warmth in the tubes helps to make them more pliable and fit on things better) but don't put too much pressure on any glasswork, it's annoying to break new bits.
Also, make sure that you put the non-return in the right way around, they've usually got an arrow on them, but if necessary, blow through them.
Personally I'd get the drop checker first, and then get things going.