If i want to make a cataloge/brochure using illustrator...?

I did make the design for a catalog using illustartor.. but the thing is that i designed each page sperately .. it is a 2 double faced pages catalog which to be folded in half .. so is it a problem for the printing company?? or should i design every two pages together on the same doent and put the folding/crop marks ?? pleeeeeeeeeease help a dummy designer like me!!!