Ok all you smart people I have a favor/question for ya. I have a Garmin Echo 100 on the front and a Humminbird 757C on my console and all I know how to do is read the depth and see blips go across hoping that's fish. Are they a way to know what I am looking at as far as types or sizes of fish? I am dumb at this stuff but want to learn it badly. Any direction would be greatly appreciated in advance..