Does the phone or phone's SD card show up as a drive letter on your PC?  Treat it like any other drive, or folder - right click and select New...Folder, name it accordingly.  Then drag the files you want to the folders you've created.

I'ts a bit more tricky to move things around via the phone and a file explorer app, but it can be done using long presses on the files and folders to get options.  But, as long as you are using the computer to move the files to the SD card, it's just as easy to create the folders and move the files wile you are on your computer.