Submit them to magazines first, then sell them. If you want, put a free coupon on your web site so people can download them from Smashwords.
But free basically means that a hundred people will download them for every one who reads them. And a few percent of the people who read them will post one-star reviews because 'this is a -- insert genre here -- story and I hate it because I don't read that kind of thing'.
Also, Amazon seem to frown on putting your stories on your own site for free and then uploading them for sale.