USB storage and read/write access

Hi, so I'm currently sharing a hard drive for the network, but I would like to add a password for read and write to it. The sotrage works well when I access it, I can add folders, move folders, copy folders, play music, etc. but when I go to my routers IP and I go to advanced settings for USB storage and I press edit... nothing happens. Maybe I'm doing it the wrong way. Can anybody help me please?