What types of clothes would common people in fantasy wear, i don't mean the people going on adventures and rushing into battle i mean like what would a common village man or city woman wear?
There are buckets and scads of books with illustrations. Do a bit of research. It's worth spending the time because you'll get to pick the look that strikes your fancy. And since it's fantasy, you don't need to worry too much about being anachronistic (a common mistake in historical fiction is to project early modern wear back into the Middle Ages).
But, really, why do you want to know? Is describing the clothing of a passing peasant important to the story?
Well it depends what kind of era your fantasy world is based on, so some basic research is rewarding for a few ideas. If your world is basically medieval European this link may give you some ideas:
What Ireth said, then. Also common was what we would call a simple shift, almost like a dress. If you'd like some quick ideas, search on "tres riches heures" and then go to the images tab. It's a book of hours done in the 14thc and has a wonderful outdoor picture for each of the twelve months. Plenty of peasants in there, plus nobles and a few other types.
In a western medieval setting, the common folk would likely have wool for their clothing rather than cotton. Of course, I suppose it depends on your world too, like if your world has more cotton fields than sheep herds In fantasy, it's all up to you.
Aristocrats would pass down their used clothing to their employees as part of their annual salary. Fashion usually imitates what every thing king and queen are wearing. The 'fashion' of poor people is maybe 20-30 years behind the fashion of the aristocrats. (especially is you are literally wearing the discarded clothes of richer people.)
Those are some generalized ideas from my costume history class. For specific details, Wikipedia has a small amount of info on each costume period in history.
Try this on for size, I started making a visual thesaurus for fantasy writers a little while ago (at first I thought it was going to be hard, then after creating three pages I realised it would be next to impossible).