Incorperating logo's into phpshop

ok i have d/l’d phpshop and now I would like to incorperate my logo’s into the design. How would I go about this? Do I need to upload the phpshop files to the server first then add the logo’s by renaming the gif files to the same as the logo’s that are there? or do I need to add them before uploading them to the server?
I know absolutely nothing about .php so any help on this would be greatly appreciated. :smiley: