During my VPS there's just one user known as root and a few groups, how do i create more customers and groups with names of my choice ?

During my httpd.conf file there's

SuexecUserGroup "#501" "#501"

What's the concept of this ?

Re: how do i create more customers and groups

man adduser
man addgroup

Make certain to complete adduser/addgroup having a user with permissions in a position to update /etc/passwd and /etc/group. Or sudo.

Re: SuexecUserGroup "#501" "#501"

See http://httpd.apache.org/docs/2.2/mod/mod_suexec.html