There are many places to go to start an online store.
There is Amazon.com you can become an associate and open an amazon AStore.
Then there is Zazzle.com and Cafepress.com
You can also go to ebay and open a seller account and then open a store.
These are just a few of the places I know. If you want to have your own shopping mall then go to www.ourgv.com/jaciclayton sign up for a free shopping mall and promote it to make money for yourself and non-profits
There is affiliate opportunities as well.
Hope this helps