Alpha channels

[levibisonn]

Hi all! I know there is probably a solution to this already on here but i have already spent hours trying to figure it out.
I am trying to make a render that is transparent through transparent parts. i have tried making a render layer with all of my transparent parts but i cannot seem to get it to work. When i render the image, the layer that is has the transparent pieces is transparent around the edge of but isn't simi-transparent through the piece (you can see the green background through it)
-thanks in advance!