does anyone know what holds the screen frames in? What do they look like and where can they be purchased.

The window frame. In the window frame there will be three slots. The outside one holds the movable glass, the second hold half the screen and the third the movable half of the screen.

They are probably Hehr windows.

There must be some kind of clip that holds it in the track that is missing and that is what i am looking for.

Mine are held in by channels, which slide away from the screen bottom to allow removal.