Hi Marianne,

Groups did an update the other day and we haven't had a chance to update all of the information documents so when you go to the Case History group in the files section there's now just one button that says "+New" with a little downward facing arrow.  If you click on that button it will then show a drop down list and "New Folder" is an option under there.  

Hope that helps and from that point you should be ok (although again, once you've created a folder the button will still just say "+New" and need to be clicked on to select "Upload File").  Let us know if you get stuck!