How do you make see through windows?

Sorry another question again, this will probably be my last. But yeah, how can I make see through windows?

Two ways to do this.
1. Fill in the places in your texture that you want to make it transparent with a single color. The norm is pure blue (0 0 255), although you should choose other colours if there are areas coloured blue in your texture, or else those areas would become transparent too.
Then, edit your objects that uses this texture: Add the line "Transparent 0, 0, 255" after setting the texture coordinates. Then, the areas coloured pure blue in that texture will become fully transparent.

2. Use a .PNG texture. Compared with the traditional .bmp textures, png images allow a fourth "alpha" channel apart from the original three (red / green / blue), which controls transparency. This means you can even make partially transparent colours, e.g. (255, 0, 0, 50) -> 50% transparent pure red. OpenBVE can import these png textures at the expense of more processing power.

I know how to make Tinted windows