Drag & Drop File in Finder

In Finder, I want to move some files quickly between folders, but I can't seem drag and drop on this new Mac to a folder in the left margin. I am sure I could do this before on my old 2012 Mac with no issues. Now when I select a file, the file just opens, or the title is highlighted to change the name. What am I doing wrong? I've been searching for settings but so far, no luck. Any suggestions? Thanks