We appreciate it but tell me how you did it i just wanna know for personal use in the future!
I have used fireworks for this job, but you can use photoshop or anyother graphics software.
For fireworks, simply open the Gif animated image and simply go for "save as", right before when you are about to give your image a name, you will see options button under "save" button. (in photoshop this option automaticaly pops-up after you save).
Now you will see a window will pop-up and this window will be showing you Whole lot of options to choose for your gif image.
Left panel will be for settings and right panel will show you "preview".
Now from the left panel choose "index transparency" and select the colors you want to set transparent and save your image.