Get an old squirty bottle, fill it with soapy water. Spray the soapy water on the rear window and the tint film. Put it on, push the air bubbles out. Push the air bubbles to the closest edge. Then, as has been said, any you cant push out heat up with a hair dryer
The soapy water will let you move the tint film easily, and wont stop it sticking when it drys
Good luck