Lets start with the valve.

1st put the valve spring on the cup seal

(tip crush the end of the spring in a little like in picture 2 this will keep the spring on the cup seal)

screw the valve onto the valve tool then insert the cup seal into the valve

next and some oil on the valve o-ring and insert it into bottom section of the gun.

As you push it in turn the valve clockwise to make it go in ezer.

Once you have the valve where you what it ( ......adjust velocity both
 Bolt & Valve  ) put the two valve screws in