For adding a new user first login as root using su – then use command useradd username this will create n new user to check detail of user use id username it will show user detail.
login as root
[abc@localhost ~]$su -
give the following command
[root@localhost ~]#useradd manish
check user is created or not
[root@localhost ~]#id manish
uid=501(manish) gid=501(manish) groups=501(manish)
it will give id of user if it is created
assigning password to manish
[root@localhost ~]#passwd manish
Changing password for user manish.
New password: linux
BAD PASSWORD: it is too simplistic/systematic
BAD PASSWORD: is too simple
Retype new password: linux
passwd: all authentication tokens updated successfully.
You have created user manish with password linux