Q:

How do I heat up pre-made crepes with cognac? 

I bought some pre-made crepes from the store the other day.  I know that when making crepes, cognac is used.  The advice I found online points to heating the ready-made crepes in the microwave (I don't think this is a good idea) or the oven. 
I happen to have some cognac, and was wondering if it is a good idea to heat up the crepes with the cognac.  If so, what would be the best way to do this so that the integrity of the crepes and the texture and flavor are best preserved? 
I am a relatively beginner cook, so I know this may be a very stupid question, but any advice would be very helpful. 

A:

Given that you ask about flaming cognac, I'm going to assume that you're making Crepes Suzette. 
If that's the case, it's not complicated.   Follow the recipe I just linked; you'll see that even though it includes making crepes from scratch, that's a separate, first step.   You then heat the crepes in the orange butter and sugar.   if they are too dry to fold, heat them briefly in a dry pan over low heat. 
Flaming with cognac is the last step, and it's done by setting fire to the cognac in a cup and pouring that over the crepes.   Again, this is all in the classic Pépin recipe I linked above.