===== Changing the header logo =====
This really depends on the template you are using, but generally, you can change the logo graphic by editing the main_page.tpl.php file in whatever template's directory you are using.
For example, in the default osCmax **fallback** template, depending on the version you want to find the below lines and then change the image name to your custom image name.
Version 2.0RC3 this is called:
'oscmax.gif', 'osCMax v2.0 - Power E-Commerce'
\\
\\
\\
Version 2.0.4 and more current (v2.0.25, v2.5) this is called:
'store_logo.gif', STORE_NAME
Change the name of the image above to match your new logo. Then make sure you have uploaded your new image to the /images/ directory of your store.