Unity 2D Platformer Tutorial 8 - Introduction to Scripts in Unity 

Make sure the script's class name is the same as the script's file name, starts with an uppercase letter and contains no spaces. Save the script before attaching it to an object.

@@danielkwood When I right click on it and view it's properties, it says under Assembly Information that the filename is "Assembly-CSharp.dll". But when I open the script and go to save it as, it shows the file that was already saved as "MyScript" so now I am confused. How do I change and make sure it stays the same?

@@stealth_meister4939 Try deleting the script and creating a new one. Name the script eg. PlayerController, open it, edit and save the script and then attach it to the object in Unity.

@@danielkwood Just did it. Worked. Thank you.

You need to open with something but that is all I know sorry

go to edit then preferences. click external tools and then you can select the External Script Editor.