1. Go to the uBlock Origin Releases page at GitHub (a version-control repository and Internet hosting site).
2. Scroll down until you see a heading for "firefox-legacy" in blue letters, followed by numbers.
3. Now we install the extension.
a. Look under Assets, and you will see the link for the package uBlock0.firefox-legacy.xpi . This is the XUL edition that will properly function in Pale Moon.
b. Click on this link. Click "Allow" if prompted by a pop-up.
4. Now look in your Add-ons Manager. You should see uBlock Origin installed with the beloved Blue Dot.
5. Optional step:
Install JustOff's uBlock Origin Updater. This will automatically update uBlock Origin so that you will not have to repeat steps 1-4 in order to update the extension.