Ok I get it now, I need to remove the yellow jumper after programming it otherwise everything is erased when I remove and replace the power source.

Wondering though if there’s a better procedure regarding reprogramming it than having to keep putting back the jumper, and if it’s safe to remove and replace the jumper while power is on.

And I’m still looking for the spec sheet.  Thanks.

Hi Johann Tagle, 
For some reason the notifications stopped working for me and I didn’t receive the new forum posts, that’s why I’m taking so long to answer. I saw that you’re posting your questions on Facebook too, that way you can get help from more people and quicker. Thanks for your patience!
Yes, you’ll either have to place the jumper wire or add a push button to your circuit that would make the same effect. Either way you’ll always have to connect GPIO 0 to GND in order for the ESP to start in flashing/uploading mode.
Regards,
Rui

Thanks Rui.  I actually posted here while I was waiting to get into the FB group.  Once I got in, you can see I can be quite active 🙂

Anyway, regarding this, is it save to remove and replace the jumper while the unit is powered on or is it best to do that while power is disconnected?

I had a problem with my Facebook account and I couldn’t add anyone to the group for 30 days, that’s why I it took so long. Thank you for understanding!
You actually need to place the jumper when the ESP8266 is disconnected from power, because when the ESP starts GPIO 0 must already be connected to GND in order to go to flash/upload mode.
You can also have GPIO 0 connected to GND and press the RESET button, so the ESP starts while GPIO 0 connected to GND (meaning that it also goes to flash/upload mode).

Yes but after flashing it is it safe to remove the jumper while it is turned on?

Sure! You can remove after upload your code. In fact, you need to remove the jumper, otherwise the ESP8266 goes into uploading/flashing mode and it will not run your code, because it thinks you want to upload code again.
I hope that helps!

Actually it gives errors if I try to upload more than once.  I need to power it off first.  Curious, how does NodeMCU and the like handle this – because they just allow me to upload code anytime, without having to change and settings.  I just need to connect the USB cable connected straight to them (no FTDI).  Thanks!

Yes, you need to power it off first, please read point 2. below 🙂
Here’s what happens in different scenarios:

1. If you want to upload code to your ESP, the ESP must boot with GPIO 0 connected to GND to go into flash/upload mode
2. If you upload a new script to your ESP, after the code is uploaded – the ESP starts running the new script even if GPIO 0 is still connected to GND. However, to upload new code, you’ll need to restart the ESP again with GPIO 0 connected to GND
3. If you restart your ESP while GPIO 0 is connected to GND, it will start in flash/upload mode and your ESP won’t don’t anything (it will not run the new script)
4. If you want to upload a new script to your ESP – the ESP needs be restarted or powered while GPIO 0 is connected to GND

So, you need to restart your ESP with GPIO 0 connected to GND to upload code. OR Remove GPIO 0 connected to GND to run your scripts.