Menu backgrounds - SuperCatGaming/Velocity-Redux-Mod-Creator GitHub Wiki
If you are following the recommended file structure for mods, menu backgrounds are located under [MenuBackgrounds]. It is recommended to create a folder for each menu background you add.
To create a menu background, you first need a prefab. To create a blank prefab, access [Assets > Create > Prefab].
Open the prefab by double clicking on it. You can create custom terrain, add models, and add pretty much anything else that you want to your menu background.
After you have everything added in that you want, you must add a "SpawnPos" object to this prefab, as it tells the game where to spawn the car in the scene. You can find this object at [Assets/Common Resources/SpawnPos.prefab].
Add it to the your menu background prefab by clicking and dragging it into the hierarchy. Finally, position it where you want the car to be placed in the scene when this menu background is selected.
[!Tip] Position the "SpawnPos" object slightly above the ground (~1 unit should be plenty) to be sure that the car doesn't sink through it. Also, remember to have the move tool selected so that you can see where the object is located.