help on basics of ethernet interface

hi all

 I am a newibe. i am tring to send bit stream data through ethernet. i
am using altera DE2 board. i have my data in SDRAM and interfaced onto
the etherenet pin by avalon switch fabric.
 The doubts what i am havin are i know the basics of TCP/IP. according
to that ny data packet should contain UDP/IP address.. etc.. how to
prepare my bit stream data in SDRAM so that it is made compactable for
data transfer. i mean have to make the data packets that will travel
through the ethernet. i am using UC/OS II rtos and NICHESTACK TCP/IP
Stack