I've done a little bit of arduino nothing too impressive, and I've had basic physics. I'm still having issues understanding how graphs(the data structure) come

I've done a little bit of arduino nothing too impressive, and I've had basic physics. I'm still having issues understanding how graphs(the data structure) come into play and how to count the resistance in those situations. I've read several books on basic electricity. As for calculus I've only had calc 1. What should be my path to learn more about these simulations?