from where? if you just wanted to export that file directly ct2 or tinke can do it. but if you mean extract stuff from a dat file, you may want to include more details like from what game, what type of compression it might have, what you are trying to extract from it?
or any other details that won't leave people going "huh?"
take a look at the wiki on the top of this forum (a good look). the one on rom hacking.
if you want to read the dat file again tinke and ct2 can both let you do that.