locale not set, how do I set it?

[riechert]

I have 3.4 installed to the hard disk. Trying to install software with KPackage. It succesfully get the packages but when it tries to install I get the following:
perl: warning: Setting locale failed
perl: warning: Please check that your locale settings:
LANGUAGE = (unset),
LC_ALL = "en_US",
LANG="C"
are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_MESSAGES to default locale: No such file or directory
locale: Cannot set LC_ALL to default locale: No such file or directory
and then a bunch of dpkg-deb: subprocess tar killed by signal messages.

How/where do I set the locale

[pulsar]

Try under Settings: Control Centre (kcontrole)