where to go to add a user in ubuntu (New to Linux)

Where do I go some instructions say go to root dir and type (where do i do the following and how do I get there) I am new to ubuntu and I got this far (true Blue IBM er ) until New Years Eve?

useradd

The useradd command will let you add a new user easily from the command line:

    useradd <username>

This command adds the user, but without any extra options your user won’t have a password or a home directory.

You can use the -d option to set the home directory for the user. The -m option will force useradd to create the home directory. We’ll try creating a user account with those options, and then use the passwd command to set the password for the account. You can alternatively set a password using -p on the useradd command, but I prefer to set the password using passwd.

    sudo useradd -d /home/testuser -m testuser

    sudo passwd testuser

This will create the user named testuser and give them their own home directory in /home/testuser. The files in the new home directory are copied from the /etc/skel folder, which contains default home directory files. If you wanted to set default values for your users, you would do so by modifying or adding files in that directory. If we take a look at the new home directory for the user: