I also can't change the theme of it or customise it.
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Go to Dashboard > Appearance > Themes
type in the name of the theme you want to use
click the "activate" link when it appears
After you change your theme all you need to do is go here Dashboard > Appearance > Widgets > Inactive Widgets and re-install them where you want them to appear. The widget contents and settings will be the same as they were prior to changing themes.