First let’s drag our picture into Unity. Once you’ve done that select it because we are going to change some settings in the inspector panel. Choose Advanced for texture type. Under mapping choose Latitude-Longitude Layout.
Next right click in the project tab and create a new material.
Under Shader> choose Skybox/Cubemap and then drag your image onto the material.
Now go to window>lighting and choose your created material as a skybox
Hit Play in the editor and you should have a fully functioning 360 Skybox