Admin CP> Skinning and Styles> Image> Logo
Put the link to the image there. To get a link right click the image and go to save picture as to save it to your computer. Go to imageshack.us or tinypic.com and host the image there.
Lets live together, I don't know how long it will last, but it doesn't have to be for show, together, till death do us part. - Kenshin "Shinta" Himura - Rurouni Kenshin