sd card does not appear when connected with usb

I recently got a Motorola Photon and have just recently gotten around to setting ringtones, wallpaper, etc., using my own files. The wallpaper worked fine using an image on the SD card (which I transferred from my last phone), but I can't access the ringtones on the card. I can go to the card using Files and all my ringtones are still there.

Reading here and other places, I understand (...I think...) that I need to create a folder called "Ringtones" in my Music folder, and then copy my ringtones over to that new folder. Problem: When I connect the phone to my PC to do things like create folders and copy/move files, the SD card doesn't appear. For that matter, no folders appear.

What I do get is get Autorun, config ins MML_Installer, run, and setup (the last one has a Motorola icon). Nothing at all that I can see to click to make the SD card appear, much less move/copy things on it, and nothing I can see to display the Music folder that's already on the phone.

What am I doing wrong?