Let me give you some advice cause when i was working at Best Buy, I would do these all the time.
First take the solution that comes with the package and spray it on your screen and the back of your shield (the stickier side).
Then spray the front side of your shield too, make sure your shield is wet. It's more important for the shield to be wet, but having the screen be wet is important too. Make sure you have a good squeegee. The one that comes with it is crap. I would recommend something rubbery, not a credit card. Doesnt have to be large, about one inch (sorry I'm US lol) is fine.
Line up one end of the shield (so for example, make sure the bottom is lined up) and lay the rest of the shield in place. Squeegee from the bottom up (or vice versa, wherever you first placed the shield). Squeegee in small, short motions. Dont go all the way from one end to another..take your time.
If you placed the bottom and lined it up correctly, once you get to the top it should be straight. Let me know if you have questions...lol. These instructions aere better seen than read.