Ok First Just Make A 450x by 100x transparent backround
Next Make A Backround Of Your Own
mychoice

Go To: Image>Canvas Size>500 pixels by 400 pixels
Paste Your Image
Add Some Stuff On
Next: Save As.....file of type:PNG (*.PNG)
With No Interlace
And You Should End Up Wit This:

user posted image
and if u really put hard work too it u should end up wit this