Reading Electrical Schematics

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Can someone who understands Electrical Schematics help a beginner out (easy)?

I want to build a light strip project I saw in Popular Science for a small indoor greenhouse for my plants. I want to add an optional light-sensitive ajustable intensity circuit to the control box but I’ve never learned how to really read a schematic. I can build and work visually, I’ve fixed my own TV, etc. but this schematic is confusing me:

http://www.popsci.com/content/grow-lights-schematic

What’s up with all those ground symbols? Why is there a ground symbol between the 10 ohm resistor and the potentiometer, and why does it say “gnd” in one spot but use the regular symbols in others? Is the top diagram just an exploded view of the potentiometer portion of the bottom one? Help?
Yeah it definitely sucks.

The schematic sucks. Even people that make schematics can be quite retarded.

The GND that’s written goes to the source of power. Beyond that its pretty confusing.

MAP Sensor & Wiring Diagram