Hi, the $this->getLogoSrc() gets the logo URL from the Admin. Specifically, it refers to the image you specified at “System/Configuration/(General Tab)/Design/Logo Image Src”, normally “images/logo.gif”. This image is to be placed in the “skin/(yourtheme)/(yourskin)/image folder”.
If you want to use another image, just place it in that image folder and refer to it in the admin: image/mylogo.png or what you want.
So in this case, you just need to choose another image and not change any template (you could however do this by using the following code).
Generally, though, you refer to skin images in the templates simply via the following code:
<img src="<?php echo $this->getSkinUrl('images/myimage.jpg') ?>" />
Edit: getSkinUrl, not getUrl. It was late.