You probably want to ask FB on attaching article since that is their site and they could have some site restrictions or the actions may be different when your on FB.

If you want to share a link, you can use Copy Link. When you paste a link on Facebook, FB sometimes will grab a thumbnail of the article and insert that along with a summary. But it depends on the site, sometimes you just get the URL.

When I start composing a post, I don't see a method to attach a file (like a PDF), just a photo/video. This would be something you already saved to your computer rather than something grabbed directly from a website.

Some FB Groups have a Files section where you can upload a file. I suspect that is a separate step from adding a post about the file, but I haven't tried it myself.

Hi markwarner22, Already tried that. Got no response from Facebook.

Hi, jscher 2000. So copy link is the correct option to use of the available options.

 Your comment, "When I start composing a post, I don't see a method to attach a file (like a PDF), just a photo/video. This would be something you already saved to your computer rather than something grabbed directly from a website." So, how do I access what I have saved on my computer to insert it (attach) on a FB message I'm replying to? 
   Are there specific instructions that Firefox has to follow or accomplish the task of inserting (attach) a website article to a FB message that Firefox may have instructions for, jscher2000? That would sure help. Trying to contact FB for help, which would seem to be the best option, didn't work. I can't get a reply from them. So, that is why I turned to Firefox for help. Appreciate your help jscher 2000.

jscher 2000, Why is it when I reply to a Firefox reply, my response comes out in the segmented way it does? It makes it hard to understand the way Firefox presents the reply. What am I doing wrong? How do I correct the problem? This not the first time this has happened when I try to reply. Thanks, jscher2000.

Hi, on this forum, if you start a line with a space, it uses <pre> tags without text wrapping, similar to how you might want computer code to look. So don't try to indent any lines in your reply unless you want that appearance. Probably you can use the three-vertical-dot icon next to your reply to edit out those spaces.

Your comment, "When I start composing a post, I don't see a method to attach a file (like a PDF), just a photo/video. This would be something you already saved to your computer rather than something grabbed directly from a website." So, how do I access what I have saved on my computer to insert it (attach) on a FB message I'm replying to? Are there specific instructions that Firefox has to follow or accomplish the task of inserting (attach) a website article to a FB message that Firefox may have instructions for, jscher2000?

Right now, I only see a way to attach a photo or video from your computer (click the button for that), or a link to the web (paste the link into your comment). The only place I see to upload files like PDFs is in a Group, there is a Files tab for sharing files.

Have you seen other people being able to attach files to their comments? I'm not a big Facebook user, just two to three times this year, so I'm not aware of all the latest capabilities/restrictions.

 tags without text wrapping, similar to how you might want computer code to look. So don't try to indent any lines in your reply unless you want that appearance. Probably you can use the three-vertical-dot icon next to your reply to edit out those spaces". I will certainly see when I reply here. When I access those 3 dots, Quote, Edit post I guess edit post is the right option? Just sort of confused that is happening when it appears to me I'm writing out a message the way most would right out a message? "Starting a line with a space" you must mean starting a new paragraph? Usually when you start a new paragraph you create a space when doing so in most English grammar. So, going forward I guess I should avoid creating a space when I start a new paragraph? 

Your comment "
Right now, I only see a way to attach a photo or video from your computer (click the button for that)" Is that button the copy link button? I haven't tried pasting a link to my message response yet. But that was on my radar. Thank you, jscher2000.

jscher2000, not sure you got my many follow up responses regarding the type issue and using the 3 dots, Quote, Edit post. Sort of chasing my tail here so I hope you got those replies? Can you please let me know if you got those replies? Thank you, jscher2000.

I only see the replies here on this page at https://support.mozilla.org/en-US/questions/1476245