Run Python Script on Start up

In Blender Render (bpy) how can I run the python script on start up. So as soon as the file is loaded the script runs without having to click the Run Script button.Or is there a way of creating an executable file with auto runs?

Make it into an addon.

Thank you for your help, but how do I make it into an addon?

Add a bl_info entry at the top of the code, then wrap the script inside a class and register that class with bpy.utils. The docs and templates have some examples.

Docs are on

Templates can be accessed with Blender’s built-in text editor.

You don’t have to make it into a addon. You can just place into scripts > startup folder.