easy
step 1, clean the windows inside and out
2,wet the outside of the window with water, stick the film to the outside and cut the tint to size making the film 3mm smaller then the glass (make sure the sticky side is facing the outside)
3, split the films and apply to the inside with water, slide the tint around and get the air out
4, now get the water out with the squeegee
for curved rear windows you'll need to cut the film in to horizontal strips. this leaves a visible line
you can overlap the strips and carefully cut though both films and peel off the excess
or you can try and hide the gaps behind the heating eliment
also it easier to do 4door cars as you can take the windows out