Petty traders in the context are the street marker retailers who sell directly to end producers. They gather in local markets and streets.
Well, if you wish to educate the petty traders about Bitcoin, you can go do it individually or organise a market public lecture to educate them.
But I will strongly advice that you shouldn't teach them to adopt it in their business. Many of them don't even balance their accounts and they are always confused with finance, especially the aged ones. Don't bother to increase their problems. You can teach them about Bitcoin and they will decide whether or not to involve it in their business when they must have gotten the full understanding of bitcoin.