Getting the "adduser" script to work on Linux

" Hi, I'm a very beginner at shell scripting and unix/linux. I have your book (Wicked Cool Shell Scripts) and it is really great. So far I've done two or three, Inpath is the one i use most. I'm going make a user for an ftp account so my friends can upload/download songs and other files. I decided to use your adduser script for the job but when i run the script i get an erorr like - /etc/passwd : permission denied. How do i give the script permission to write to /etc/passwd? Sorry if this is an obvious question but i couldn't find an answer. I used chmod 755 and ran it as root. By the way, i really like the site and book cover, i wish all linux/programming manuals had really cool covers."