Start here, https://learn.sparkfun.com/tutorials/rn-52-bluetooth-hookup-guide, follow through the suggested reading as it goes into depth about electricity, circuits, capacitors, diodes, and resistors. I really feel like I’m learning a lot from this.
Making a Bluetooth Rotary Phone part 9
The site I’m reading to learn about circuits is really good. This is the same company which sells all the components I’ll be buying to make this happen.