https://ibb.co/g2PxUf as you can see in the screenshot, a forest is surrounding borders of skybox. how can i make like this? i use the sky_trainyard_01 thanks for answers.
They're props using skycard models in the 3D skybox. Search for "skycard" in the model browser and place it in your 3D skybox if you have one. If you don't, you need to create one to contain them.