I installed wordpress on my Ubuntu 12.10. The website loads perfectly on localhost/wordpress.
I cant install new themes through the dashboard->Appearance->Themes->Install New themes way. I understand it is because of the permission issues.
In the past I remember overcoming this by problem a few years ago on some other maching by manually copying the theme folder in wp-content/themes folder.
I did the same this time but even after copying the files. I dont see the theme listed in the installed themes page.