Custom background with lights?

Hello, I am new to custom builds. Just completed my first one, which was pretty basic. Used foam board, expanding foam, drylok. But now I have the itch to push my skills further and I came across this photo!

Could anyone inform me on how I could incorporate lights into the background. Would like to do a mossy cave theme with bioluminescence and some light up crystals/stalactites.

All thoughts, and advice are welcome! Thank you!