Ethernet Code for LPC 1769

Hi all,
We are planning to use Ethernet in our project with LPC 1769 processor. We are using DP83848(national instruments) transceiver.

The problem for me is that i don't where to start with. what are the steps to follow to write code for ethernet. Why should one use TCP/IP stack? How to test the code we have is correct or wrong??

Please guide me through this....

Thanks,
Pavan