Assuming you've created the folder /lib/firmware using "sudo mkdir /lib/firmware", then you should be able to copy the firmware with "sudo cp /path-to-file/rt73usb.bin /lib/firmware"
Note that unzipping the firmware might (re)create the original folder structure, so if you unzipped the file in /tmp, it might be in /tmp/some_folder_name/rt73usb.bin
The emelfm extension might be useful for navigating around the tc file structure?