Use the adduser command to add a new user to your system.

$ sudo adduser username

Set and confirm the new user’s password at the prompt. See Password Management

Set password prompts:
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully

Follow the prompts to set the new user’s information. It is fine to accept the defaults to leave all of this information blank.

User information prompts:
Changing the user information for username
Enter the new value, or press ENTER for the default
    Full Name []:
    Room Number []:
    Work Phone []:
    Home Phone []:
    Other []:
Is the information correct? [Y/n]

To add a home directory for your new user

mkdir -p /home/username

useradd -d /home/username username

If the username has already been added using useradd, then you can use usermod.

usermod -d /home/username username

For how to make the user a sudoer go to Add a User to the Sudoers Group

For how to change your password go to Change Password