the best thing you can do it get it on the ice and play with it. Try all the different settings, move the gain up and down, zoom in and out.
Jig, watch you jig move on the flasher, get a feel for it. If you have some lakes that you are familiar with the bottom structure, then take your flasher and see how it responds, so when you are on an unfamiliar lake you will bee able to read it.
the manual help, but you need to get it on the ice to get a true feeling for it. Talk to other flasher users (even if they dont use what you use)