Gridlocked Theme

Despite how easy people say it is to use Gridlocked theme, Im struggling. Admittedly Im new to WordPress but Im pretty computer literate and still cant figure out where Im going wrong. Apart from problems with general layout, I cant figure out how to change the logo from the default Gridlocked logo. WordPress wont let me upload one in the ‘Custom Logo’ section of the theme, there is no error or anything, just when I press Upload Logo, nothing happens. So, I tried downloading the PSD off my FTP, changing the logo within the Logo layer, resaving and reuploading but that hasnt worked either. My other problems include not being able to see the default background image, and not being able to make posts that look like the ones advertised in the theme.

Any help to any of these problems will be much appreciated!

Thanks!

D