How can i make my banner transparent PLEASE HELP !!!!!!!

hey i started my own forum and at first it lookd like this
[You must be registered and logged in to see this link.]

[You must be registered and logged in to see this image.]

and then i want to replace the robots with this image that i made on photoshop and i want to make the white background transparent like with the robots [You must be registered and logged in to see this link.]

i know that i cant save it as jpg becouse it will not go transparent on the site then i tryed to do gif and it lookd really bad so i dont know what to do now so please tell me how i can make a logo like the first one the robots PLEASE HELP !!!!!! OR IF YOU COULD MAKE IT TRANSPARENT HERE IS THE LINK !!!!!

JPG ---- [You must be registered and logged in to see this link.]
PHOTOSHOP ---- [You must be registered and logged in to see this link.]

You need to save the images as .png when you create them.

thanks i will try it right now

OMFG it works thanks omg YES!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!