Once set up, do your shopping at smile.amazon.com and that percentage will get sent back to JeffStreet.
Register on the Amazon App
In the app, type "amazon smile" into the search bar.
Click the header that is telling you to "visit the amazon smile settings.
Once there, follow the prompts to search for Jefferson Street Christian and set the church up as your charity.
You can then continue to shop in the app as usual.