You may use AdBlock Plus: https://addons.mozilla.org/en-us/firefox/addon/adblock-plus/

Although I do plan to use your suggestion to escape annoying ads, I need to know how to ALLOW pop-ups (which is the same as disable the blocker) from a certain site. I need to complete computer courses as part of my job, and the instructions mandate that I disable the blocker

On Firefox for Android, you may try these:

• Type about:config in the address bar
• Search dom.disable_open_during_load and set it to false