You should be able to find your device in Device Manager, under Ports, as COM1, COM2, etc. If you cannot see your ESP8266 there, then you might not have the necessary drivers installed.
Download Drivers Here: nodemcu-devkit/Drivers at master · nodemcu/nodemcu-devkit · GitHub
After installing the drivers, While the Device Manager is open, connect your ESP8266 to your PC and check if a new COM Port pops up. Then select that COM Port on Arduino IDE and upload the code.