@gglick has answered your basic questions, and his macro may be all you need.
I used this as an opportunity to build a more general purpose macro that should work with any target web page. I don't use Facebook (or its Messenger), so I could not test specifically for that case. But many web pages require some action to open and/or set focus to the text input area on that web page.
So, my macro allows for just that. It may be more complex than you need, but I hope it will satisfy a general use case. Feel free to ignore, or use parts of it as you need.
Please let us know if this meets your needs, or if you have further questions.
MACRO: Paste URL and Page Title into Another Web Page [Example]
Note that the macro uses this KM Forum as the target page for testing purposes.