how to make an subdomain service

[president]

hello
first of all excuse me for my bad english (Im an iranian boy)

now
I need an subdomain builder system there every body could chang the dns

let me tell more

for example Im the admin of gen.irgen.ir
and Id lke to have an system there every body could signup an creat her own subdomain ex: webdeveloper.gen.ir
and it be possinle for everybody to chang the DNS and useing the own hosting

regards