Haven’t played a lot with it but this should give an idea.
As tool you can use: https://free-tex-packer.com/ to create the atlas. Or check out spine itself: Atlas export format
Beeblerox shows how to use it in your code: https://github.com/Beeblerox/Simplest-Heaps-Examples/tree/master/14_heaps_texture_atlas
And some general tipps: Optimizing bitmaps - Heaps.io Game Engine
(Like always for all resources you’ll need some sort of loading/‘resources loader’, see: Resource management - Heaps.io Game Engine)
I remember there was more info in the Heaps docs but not sure…
(… And yes the idea with atlas is to merge several images into one file and have a file that describes what is in that merged file, e.g. “hero”, “weapon”, “enemy_wasp”, “house” etc. and they can have individual pivots - I guess? - and stuff)