1. Wire up the ESP-01. To prepare it for firmware flashing, GPIO 00 should be connected to ground before you apply power to the ESP.
2. Visit www.nodemcu.com
3. Navigate to Github to download the firmware.
4. You can download the actual firmware binaries in pre_built. However, it's even easier if you download the flasher itself because it has the firmware included in there! Get the 32bit or 64 bit version depending on your PC's OS.
5. Run it. Yeah, you'll get unsigned app warning.
6. It should find your FTDI port automatically. Click Flash button and wait till you get a checkmark at bottom left.
7. Quit the flasher app.
8. Connect GPIO 00 to vcc (via 1K resistor if you have it, but I've connected it without a resistor also). Recycle power on the ESP. If you forget to do this, the next step will not work because it thinks that you're going to re-flash the firmware.
9. Use some sort of a terminal program to connect to the FTDI port. I'm biased towards LUA Uploader (I wrote it :-))
10. Write a hello world lua progam.
11. Have fun!