To Change this weeks mailer page go to running theme's Customization section.
Then click on "Shop this week mailer (blue image)"
Then on the right side you will find "Mailer page"
See image below --
Fill those information.
To get map coordinates click on the blue line "Find your coordinates"
Paste address here and click "GO". Scroll down a bit and you will find coordinates on this page.
Copy those values and paste the in latitude and longitude.
Then go this link and right click > inspect element > source > files > large >1.jpg
Then right click on that image and save it. After saving it upload under "image" section and save.