Go to back-end of your site via https://parrotfish-wrasse-a78h.squarespace.com OR https://account.squarespace.com/ (bookmark one of these for easy access)
Click on PAGES in Menu.
Click on page you want to add new project to (e.g. Editorial). Scroll to bottom of list of galleries and click ‘ADD NEW PAGE OR GALLERY’.
Change name of Gallery to name of Project (e.g. Harper’s Bazaar).
Empty gallery will open. Drag and drop images in (make sure you’ve already resized your images to below 500KB each using app such as www.tinypng.com). Reorder images by dragging.
Click on Settings Icon to make sure Titles are right and URL is unique. Click on Media tab to make sure thumbnail has loaded (if not, drag image in).
If you want to have your new project thumbnail show at the top of your Editorial page, go back to Pages menu and drag title of gallery up to where you want it.