DNS QUERY!!! PLS HELP

[hoi]

hi Dear,

i am a system engineer in Hong Kong,
and i am building a web sever in the company throught an ISP,
taking the leased line service from them and own 32 IP address,

now, my boss need me to build our own DNS, such that we can add and do the
web-hosting job,
i have build the DNS machine by Linux, but i don't know where and how can i
register it,
and also i wonder who i should contact with to tell them what IP is mapping
to our DNS sever?

i have register already a domain name in .com format, however the web-server
is current using a domain name in .com.hk format, would it be any problem?

pls HELP asap!

thanks very much
best regards