When using Lightroom before, I was never able to figure out how to move photos from one folder to another. You'd think that you could just click on a photo and drag it. I just spent twenty minutes figuring out what I've been doing wrong. After you've selected multiple photos, click on the photo thumbnail and not the surrounding gray frame, and then you can drag the photos to the target folder.

I had become accustomed to clicking on the frames to multi-select photos, so naturally I assumed that was also how you dragged a set of photos. But clicking on a frame of a selected photo merely deselects all the other photos.