Changing environments?

How would I go about switching environments in a particular world?

What exactly do you mean by changing environments?

There is a folder in the gallery called Environments. Click the "Add Objects" button to get there, then navigate to the folder. There are some sky objects and a few other things like hills, lakes, and rooms.

Or do you mean the sky and ground in a world? If so, just click on the world object in the Object Tree and then look in the Details Area. The "atmosphereColor" will adjust the sky. To change the ground, click on the ground object in the Object Tree and then look in the Details Area to find a tile called "skintexture" to change the texture.

Thanks a lot.