Find or purchase a gallon plastic bottle for mixing and storage. You need a clean bottle, not previously used for commercial chemicals. Empty water jugs work well. You will also need a clean sprayer bottle. I prefer heavy duty sprayers.
Pour rubbing alcohol into mixing container.
Fill the remainder of the container with water.
Put Castile Soap into the top of the container, recap, and gently invert the container to mix.
One thoroughly mixed, fill the sprayer bottle, and use on your glass surfaces.