we'll you'll never figure it out if you don't try.
it takes two people,
the cover has to be off the inside of the tailgate, the window arms have to be above the bottom of the opening in the tailgate to fit your hands in to reach the hardware on the inside.
there will be two brackets that were on the old window, you have to find them and take the bolts out.
the grooved parts go over the plastic bushings on the ends of the window lift arms. and bolts onto the bottom of the window.
with the tailgate down and the cover off have one person on each side of the window to slide it into the tailgate.
once it is in the rails that guide the glass slide it just over half way into the tailgate. have one person move to the middle of the window and support it slightly, and to move it in or out as required.
if you haven't done thins already then slide the two brackets over the plastic bushings on the window lift arms inside the tailgate.
it is key to remember how the bolts and washers were positioned in the brackets when you took them apart.
slide the window down so that the holes in the window line up with the bolt holes in the brackets, then place the washers and bolt up the brackets to the glass.
at this point the window is in. DO NOT TRY TO CLOSE YOUR TAILGATE. you will smash your glass if you try.
if your window safety switch works then you will have to use a wrench or screwdriver to close the latches on the sides of the tailgate. once they are closed you should be able to use the window switch inside to lower the glass all the way into the tailgate.
use the tailgate handle to release the latches, put on your inside cover and you can now close your tailgate.
Mission accomplished !!!