Not dumb at all. It wires pretty simple to you bike. It's a small little box that fits in a little nook in the tail. You go to their website and use the calculator to get a number you put into the healer.
There are several ways to see how far offthe speedo is. One is an onboard GPS. or I have a speed app for my phone. It uses the GPS already in it. OR you can run say 60mph on the highway and time yourself from mile marker to mile marker with a stop watch. If your speedo says you are doing 60 but the stop watch says it took you less than 60 seconds...just do the math.
Once you get how fast you are actually going at a certain speed, you imput that into the speedohealer calculator and it spits out a corrective number to set your speedohealer with. Set it once and you are DONE!
Sorry i dont have a complete write up on it, but it really does follow the instructions that come with it well.
I was tired of calculating in my head as i rode, one of my best mods.