How to I apply semi transparent textures?

I have a bus model i’m texturing. I’m putting it into a game engine so most material properties don’t cross over so I need to make as much of the detail in the textures as I can.

I need a texture I can use on the windows. I made a semi transparent one in photoshop but it did not work.

What does your texture look like
What material and texture settings are you using ?
Are you using UVs ?
Show us something and supply a link to an example blend file (IMPORTANT - pack textures in the blend file using File / External Data menu before saving)

Enable “Use Alpha” in your texture menu (near the bottom, in a field of checkboxes), go to your Material menu and enable Transparency (at the bottom), set to Z-trans, and set the slider all the way to 0.

How to: create transparency and perform fading for all Shading modes