Windows (glass)

Hi! I would like to be able to make a window. How should I do this? I already set the render to "Transparent / Specular" but nope, still can't see through...

In the color picker, adjust the alpha of the material.

Have you assigned a texture to the material that has some transparency?

color picker only shows gray and white, what do?

I made a TutorialVideo for this, I hope this help for other people too.