First thoroughly clean the area where the decal is to be applied using a non oil based cleaner; warm soapy water works fine. And then allow time to dry.
Once you have waited for everything to be bone dry. Grab a roll of painters tape and measuring tape. Once you grabbed that. follow the directions on where the sticker needs to be placed below. (coupe shown below)
Then apply tape along the outside of the measurements lines given above.
Once the sticker is where you want it, apply pressure from one side and slowly work your way across. You may use a squeegee or your fingers. try not to apply too much pressure. Will damage the film. Now the best part is to step back and admire the new look of your car!