How to use variable level streaming?

Hello, so I want to use level streaming array variable when loading in a level. I want to use it because I want to load in a random level between 1-5. My problem is that i cant find how to add any of my levels to the array. How can I add my level to a level streaming variable?

If it’s level streaming then maybe this can give you the right idea:

It randomly loads a level from map_0 to map_5