How do I upload photos to send to Walgreens for printing, or upload to post to Facebook?

I go to Finder, click on Pictures, and I see my recent vacation photos in a single folder. I can open that folder and view my vacation photos, but cannot access them to send off for printing to a store of my choosing (i.e. Walgreens), or even post them to Facebook (i.e. in an Album from my Mac where I can see what I am selecting!). When I try to do either of these things, my vacation photos folder is "greyed out" -- not available for selecting to choose or upload photos.

I am looking for step by step help as someone who does NOT know her way around a Mac, and none of the answers or technical manuals I have reviewed addresses my problem. Many posts are older, before the new Apple photo set-up, or simply do not relate (Please do not refer me to someone else's post : )

It would also be helpful to know, conclusively, if Apple now demands that you use their printing service exclusively if you want to select/print photos the easy way from the iCloud library. Thank you!