Sorry if this is in the wrong category, if it is let me know and i will move it to the right place.

So i am trying to workout how to create a fairly complex circuit for a 3d printing project I’m doing. I know what feature components i want i.e USB-C, HDMI etc… however i don’t know where to start with functional components i.e Resistors, Capacitors, Transistors etc…

Is there any tips or process anyone could let me know so i can begin working this out.

From a very basic level I’m assuming i need to create a circuit with the feature components and then workout the voltage and ampage for input and output. at which point i can work out the resistance needed. But i don’t really know if this is correct OR if it is i don’t fully understand when i would want to consider the other functional components.

Any help would be much appreciated!