sudo Basics

Install sudo (substitute user do)

If you have used Ubuntu, you might be familiar with sudo. It allows users to run programs with privileges of another user (normally a superuser).
Using sudo, a user needn't login as a root. He can rent that privilege using the sudo command to perform privileged tasks.
To install sudo in ArchLinux:

#pacman -Syu sudo

Use appropriate package manager depending upon your distribution. In Archlinux, pacman is the default package manager.

Now I needn't use the system as root. So I create a account for myself.

Add a new user account

To create a new user account use adduser program:

Options:
-d home directory
-s starting program (shell)
-p password
-g (primary group assigned to the users)
-G (Other groups the user belongs to)
-m (Create the user's home directory

[root@myhost ~]# useradd -d/home/onie -m onie

Modify or add password
To add a password to a user account use passwd command.

[root@myhost ~]# passwd onie
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully

Switch to another user account

To switch to another user, we use the su command. This is most commonly used to switch to the root account.

Example: To switch to root account

su

(When asked for password enter root's password)

Example: To switch to the user 'onie'

su onie

(Enter onie's password)
To return to original user, enter exit

Modifying existing user accounts

To modify a user account we use usermod command.
Options:
-d home directory
-s starting program (shell)
-p password
-g (primary group assigned to the users)
-G (Other groups the user belongs to)

Deleting a user account

To delete user account we use userdel command.
Options:
-r (remove home directory)

To know more about group/user creation and modification: User and Groups Tutorial

To continue to SUDO configuration : SUDO tutorial
Sudo article from Archwiki pages: Sudo