After installing the theme you can change the logo by going to “Appearance-Theme Options”. You will find the option “Site Logo” at the very top.
In Gone – every page can have its own logo. Underneath the input field for the content of the page you will find a box called “Page Extra”. Upload a logo here to override the main logo for that page (“Page Extra” not showing? On the top right of the page – click “Screen Options” – check “Page Extras”)