Yyler, before you jump to the conclusion that everyone besides you is an idiot, you should ask what he means by the title, because the post is vauge and unclear.
Vengence, are you asking how to get the texture onto a brush, or make a custom glass texture?
You should see it when you search "glass" it is a grey icon with black lines across it. (looks just like that).
Just apply that texture to the brush.
Yes, to reiterate what Steve has said, it's not as simple as just finding the image because the image you see in game looks hardly anything like what you see in the texture browser because it does not display alpha and is rotated to 45 degrees. It can be a little confusing to find if you've not dealt with the glass textures before.
P.S. if you're having trouble finding a particular texture, sometimes it's easier just to load up one of the SDK provided maps and grab it from one of those official vmf's.