Carrara supports a number of background options. The options supported by the plugin include Color, HDRI, and Map.
Additional Background options are available in the Octane Environment scene effect.
You can rotate the background image by setting the Z Rotation override checkbox and adjusting the Z Rotation slider.
You can adjust the Gamma of the background image by setting the Gamma override checkbox and adjusting the Gamma slider.
You can also completely override the background texture and create your own texture from the available Octane texture nodes.
The Octane Texture node allows you to create your own background texture. Just remember, for images, set the Projection node to Spherical.