Basically, you fill a spray bottle with 1 part water, 1 part liquid detergent (like Dawn or whatever you use to hand wash dishes). Spray the back of the decal so it's fully wet, but not soaked or damp. It just needs to have the solution all over it. I use my finger to make sure it's spread out evenly. Make sure there's not too much where it's going to squirt out everywhere - you want the MINIMUM amount of stuff to just barely coat the back of the decal. Then put it on the playfield, you have a couple of minutes to slide it around and get it perfect. Wait for 30 minutes or an hour, you're good to go. I believe some people put mylar over top of it, but that depends on your personal preference.