To create a new shader asset, use Assets > Create > Shader from the main menu or the Project View context menu.
When you select a shader asset in your Unity project, the Inspector displays basic information about the Shader object that it defines. It also provides controls for compiling, and inspecting the compiled code.
The Import settings sectino of the Inspector lets you set the default textures for a shader asset. Whenever a new Material is created with this shader, these textures are automatically assigned.
The Imported object section of the Inspector lets you view and edit settings related to the Shader object itself, and how the shader compiler handles it.
For Surface Shaders, the Show generated code button displays the code that Unity generates from your simplified source file. If you want to customize the generated code, you can just copy and paste it into your shader source file.
You can use the Compile and show code popup menu to: