My battery was charged to 98%. I did NOT have the phone plugged into the charger. To do this your Charge phone MUST be running STOCK on Froyo 2.2.1 EE4.
I went here and downloaded this file to my PC: update_EE4B_to_EP4D.zip The file size was 117,613 KB in my PC but after it was copied into the root folder of my phone the file size was 114.9 MB.
HTTP://forum.xda-developers.com/showthread.php?t=1364298 After you choose this URL you want to choose the FIRST URL that ends in HAG3RFTBY6 in order to get the "update_EE4B_to_EP4D.zip" file mentioned above.
Next, in my PC, I changed the name of the file to: update.zip
Then using the USB cable I copied the file update.zip from my PC to my phones SD Card root file. That's where all my other stuff is stored. After you copy it there you should go to the APP My Files to confirm that it is there. The file size is now 114.9 MB.
Next I pressed three buttons at the same time (this was tricky and a bit difficult). I probably tried 8-10 times before it worked. What it was doing is turning off the phone but I kept trying. The three keys are: Home Button, Power Button, and the Volume Up Button.
FINALLY, in my case the screen that came up was a RECOVERY screen. It said recovery at the top. You will see a choice of about five things you can do. On that list of choices I touched UPDATE.ZIP and then I pressed the HOME Button at the bottom of the phone. The update started and the screen that came up had an picture of an open box with an arrow coming out going down toward a Droid. Now we know there is a little Droid doing the download! There also was a BAR showing the progress which was slow at times.
It took all of 15 minutes and then the phone rebooted itself and finally just turned off. The little Droid was probably exhausted! I waited a couple more minutes after the screen went blank (black) and then pressed the power button.. The phone started and it's working very well on Gingerbread 2.3.6.
The photo I included shows my new Gingerbread setup. To see yours go to: Settings>About Phone and then go down the screen to see the new Gingerbread specs.
Thank you HoustonHeart for all the good info. It really gave me the confidence to do this.
JerryF