Do I need to seal my concrete carport floor that's now a dining room before laying down carpet?

First of all, was there a permit pulled on turning this carport into a dining room? Most of the time for it to be considered an indoor room, you need a vapor barrier under the existing slab. If this is not the case, then if you put some type of sealer on the top before the carpet, yo could be asking for big trouble on moisture not being able to evaporate correctly and at the right speed. It also depends on the climate you are in, where your home is located. a lot of variables. DO NOT TRUST YOUR LOCAL HARDWARE STORE TO ANSWER THESE QUESTIONS FOR YOU. They are just trying to sell product and don't care about the end result. Trust an expert.