How do I make a specific color transparent?

[Guest_imported]

I've searched and Red the FM but I can't figure out how to use GIMP to make a color transparent in a PNG.

Suppose I want all white in an image to be 100% transparent. How do I do it? What menu do I go to?

 

[chanio]

First select the layer to apply the transparency.
Over that layer selection (not over the image), right-click menu & select "add alfa channel". Now you can apply transparencies.
Over the image, right-click menu & select: "Select/select by color". Now just click over the color of the selected image, and the right-click & select "Edit/Cut".
Voilà! )
Help yourself!