Making a plane transparent

I have a plane that has a semi-transparent texture applied to it. In Blender I can partially see through it, but once it’s exported, I can no longer see through it.

How can I make the plane transparent?

but once it’s exported,
exported to what ?
What are you trying to do ?
Material settings ?
What renderer ?
Render settings ?

Please supply an example blend file (pack your texture inside the blend file from the File / External Data menu before saving your file)

I exported it to a FBX file, then converted to a g3db file(which is for LibGDX game framework).

I simply want to make my plane partially transparent, so it is slightly blue, and can be seen through. A water level effect. It only needs to be like this on one side though.

Never mind. I just got it and without needing an image.

I simply added a blue material to the plane, then I simply clicked the Transparency check box in the Materials tab, then I changed the Alpha value until it looked good.