Kathy, here is how I post photos from Flickr. My search engine is Microsoft Edge. The process might change depending on the search engine you use.
You don't have to do this, but I would recommend that you open one window for Flickr and one for The Studio Commissary.
Choose the photo you want to post. I have chosen Margot Robbie on the cover of Vogue magazine. On the lower right, click on the right pointing arrow (Share Photo).
Click on BBCode
Click on the down pointing arrow to choose the size photo you want. I always pick the second medium (not too big, not too small).
Left click to highlight the link, right click to Copy.
In the Studio Commissary reply box, type in your Subject.
Right click to Paste the link in the box. If you're posting multiple photos, repeat the above process till you're done. I'm only posting one photo so I'm moving on.
You'll see the link you pasted. Click on Preview at the bottom of the page to see what you're posting. I never skip this step because you never know.
And there's the photo of the Vogue cover. What YOU see is what everyone will see once you hit post. If you don't like what you see don't hit post thinking it will correct itself once you hit Post. This NEVER happens and people do it ALL the time!
If you like what you see, hit Post and you're done! I did not hit Post because this is just a tutorial. If you have any questions, please ask. I hope this helps.
That's exactly how I do it too using Safari for Mac