DNS stands for Domain Name Services. The complexity of DNS helps to make working on the Internet much easier because most of the work of translating IP addresses and services into meaningful (and working) names is handled "in the background" by DNS servers. Their job is to know that when you type http://google.com/ you really are going tohttp://220.127.116.11/.
The basics of DNS and how it works on the Internet is covered by the article at this site:http://computer.howstuffworks.com/ internet-infrastructure.htm
The majority of DNS creation and edition features are listed under the heading DNS Functions in WHM.
This will add an A record to the DNS zone for your server hostname if it has not already ...