This is a question asked by alot of new themers.... so I hope this will be some help to you as this will show you how to make basic bars/buttons to help you on your way
I use Paintshop Pro X, but I`m sure you will get the idea and be able to figure out any software you use
First thing is to open a new image for your bar/button.... 176x26 (stardard softkey bar for SE W800) and leave the background as white

Next select a gradient colour and use the `fill` tool to colour the image

to make to bar slightly transparent move the tranpancey slider to want ever you want...but for this I`m going to put it to 55

You will see your bar has gone slightly transparent but the most important thing is when you save the image....The image MUST be saved as a .png file.so save using the Save As button

And thats it your first but very simple transparent bar...And the same princapals goes for buttons too
You could also try multi-layer Transparent bars when you get the hang of things!!!
