Creating sub-domains programmatically - Newbie

[Rashmin]

Hi,
I am quite new in the area of DNS and I wish to know how to update the database of a DNS server programmatically. 
What I wish to do is, add/delete sub-domains to the DNS database as needed, using a program placed on server, so that any user can access those sub-domains through any web browsers. 

For e.g. suppose that I have a domain name of 'mycompany.com'
Then I should be able to create a sub-domain name such as 'news.mycompany.com' on our DNS server, so that a web user can access  news.mycompany.com by entering the string in a web browser.

The DNS server will be our own standard Unix based server and not one provided by the ISP. The OS is Unix and the programming language C/C++.
I will highly appreciate any help in this regard. I tried to search the net for data on this, but was unsuccessful. 

Thanks,
Rashmin