Sending bluetooth data to bluetooth display

Hey guys. I´m kinda new to all this and I dont know much about C and C++.I can edit code but I cant put it together. I hope I will learn it but now I got this idea and cant put code together. So I got this idea of making volt meter out of arduino via that voltage sensor. Basic voltage devitor with 30k resistor and 7k resistor. I want to measure more than 5V via analog pin so I need that.

Now is hard part... atlest for me I know you coding mages can make code like that on toilet.
So I want to mesure those data via analog pin and send it thrue bluetooth to 2nd arduino pro mini and display it on 128x32 oled (with 4 pins) using probably adafruit library. I need to autoconnect two devices.

Could you give me any sugections for code or make it? As I said I can edit it change values but when I try to add something that should work it never works.

I will use this

  • "DC 0-25V Standard Voltage Sensor Module"
  • "128x32 pixel OLED"
  • "Pro Mini 328 5V"
  • some cheap bluetooth modules they should be like HC-05 I set them to speed 9600

So in my mind is. I will start voltmeter device with probes after that I will start Oled device. They will instatly connect and when I measure for example car battery it will send data (voltage) with about 250ms delay to display. And line that will make anything under 0.1V = 0V. On display there should be 4 digits like 12.38V.

Thats all. I hope you can help me. I think its nice project for everybody and we can make it work together.