Root directory question

I'm new to a Mac and got a PSP for a gift and need to know how to make a directory in the root.
This is what the PSP directions tell me: When the drive appears on your OSX desktop, create the following directories in the ROOT of the drive (i.e. NOT in the PSP directory):
MP_ROOT/100MNV01
How do I go about this?
Thanks

The directions mean in the root of the "PSP". At least that's how mine works.

how do I do that?

I don't recognize "PSP" (PlayStation Pro?), but it sounds like a type of external storage - USB hard drive, memory stick, digital camera card or some other...

Plug it in to your Mac however you normally would. After a brief pause you should see a new disk icon show up on your desktop. Double click that icon to open the root folder of the drive. Right click anywhere within the window that results (CTL+click if you are on a Mac laptop) and select New Folder from the resulting menu. A new untitled folder will appear. Type in the name you have "100MNV01" and either hit Enter or click pretty much anywhere else to complete the name entry (I am assuming that the MP_ROOT part is how it is describing the root of the device, hence I have not included it in the process). That's it - you have created the requested folder.

To eject the drive when done, CTL+Click again and select the Eject menu entry.

All done!

Got it, Thanks!