useradd - Creates a new user or updates the DEFAULT new user information

**** You need to run passwd to create a password for that user ****

useradd -D displays the current default values (these values include the default Group, Home, Shell, Inactive, Expire Date)
useradd linus will add a user with the name 'linus' and creates a login directory of /default_home/user_name or "/home/linus"
useradd -D -b /newhome changes the default_home directory to /newhome. Any new users added after this will have their login directories created under /newhome/

Some other options include:
-d to override the default home directory
-f to override the default inactive days
-D -F to set the default inactive days
-e to override the expire date
-D -e to set the default expire date

The file /etc/passwd contains a list of users, UID's and user information, including the home directory and all the finger information.

see  passwd to change the password,  chfn to change the finger information,  userdel to remove the user