Additional guidance re flashing ESP-8266 D1 Mini

[wazzac12]

HI There

Thanks for what looks like a really handy solution for my heat pump
I have not previously used or flashed ESP modules - It is slightly more complicated than I thought
I kind of assumed it would be straight forward like flashing an image to a RPi
What is the most user friendly / intuitive way to flash the module for a complete beginner? I played around with ESP IDF but no amount of searching could reveal what " Flash the sketch with flash size include SPIFFS option." meant .... I understand the flash bit - but the other bit sounds like file system formatting and I could not figure that out
Any guidance appreciaated - I'm keen to get this up and running
Thanks again for such a handy project
Cheers
Waz