Basically when the fishnet is pointing toward one direction, and price is reversing, you would look for a "slingshot" back towards the trend. Your entries can be based on candlestick patterns or some other indicator.
It's kind of like pulling a rubber band and then releasing it. You really don't need a program that has a "fishnet" indicator. For example, to make a RSI fishnet, just keep plotting a different RSI on the same chart region. Try length increments of say 10.
10, 20 , 30 , 40...etc. until you get a good looking fishnet.
I guess the point of the fishnet is to easily identify the bigger trend and timing pullback entries. Just another visual aid.