Is it useful to do the online shop?

Is it useful to do the online shop if there is only few people know your shop.

Depends what you sell.
If you want more people to know about it, then you need to advertise it online or offline.

I guess, online shopping is helpful for customer as well as shopkeepers. The Internet allows you to easily compare products and prices, so you can be sure that the item you purchase is the exact item you want. Online merchants can publish much more information about their product on a website than they could affordably publish in a print catalog and online stores give you the ability to share information and reviews with other shoppers who have firsthand experience with a product or retailer.