That's not called a spaceship script... That's basically just a movement script. For coming up with the script you can refer to various tutorials online and copy them, or refer to Unity's script reference and then piece together how you want your script to work. Is it a rigidbody? etc etc needs to be answered to come up with that script.

Alternatively, you can just get the Third Person Controller prefab and then replace the default graphics capsule with your spaceship model, if you need something so desperately.