sudo adduser john

You will be prompted for a password and for some additional information:

Adding user `john' ...
Adding new group `john' (1001) ...
Adding new user `john' (1001) with group `john' ...
Creating home directory `/home/john' ...
Copying files from `/etc/skel' ...
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
Changing the user information for john
Enter the new value, or press ENTER for the default
        Full Name []: John 
        Room Number []: 1
        Work Phone []: 555-555-5555
        Home Phone []:
        Other []:
Is the information correct? [Y/n] y