Trying to add value to a float in animator each time an animation plays.

So what I'm trying to do is have an animation play a set number of times and have the animation get faster. I've made a float and placed it in the parameter but I'm stuck with the scripting part, I have tried animator.SetFloat("AniSpeed", 1); but I keep getting errors.

I'm not sure if I'm supposed to attach the script to the animation in animator or what have you, I'm at a loss and I cant find a tutorial anywhere.

FYI Scripting newb so if you could dumb it down as much as possible for me that would be appreciated.