didnt your car com with the little license plate frame? thats how i have mine mounted. you have to use a screwdriver and mount the piece and then use the screws provided with the euro plate and screw the euro frame onto the little black piece that you first put on and then you put the plate in and then snap the(depending on where you got it from) bottom or top piece over the euro plate.
the little black piece that i am referring to is in the second picture right above the lower grill. if you dont have one, then maybe you didnt receive one after buying it. if not, then you're going to have to just screw the plate into the bumper. i dont see any other way of doing it