NodeMCU ESP8266 Voltage Monitoring

Hi guys !
Im looking to create a small project, but im not a programmer / developer at all .
I bought a NodeMcu V3.0 ESP8266 wifi , i would like to monitor external battery voltage in a trailer when its parked at my place via wifi on smarthings. I tried some stuff with Tasmota-Connect Smart App by flashing the lastest tasmota firmware to my board but there is no integration for the A0 ( Analog Input ) I would like to get a live monitoring of the voltage on my smartthings App. I know that the A0 input is 3.3V max, the voltage that would be monitored should be around 12v. Some resistors will need to be used to drop the voltage down , but i would like to scale the voltage range 0 - 3.3 v input to 0-16v displayed. but at first i would like to find a way to get some analog readings from the module to the app,

Does someone has few tips for me ? Thank You !