[Koha] i need your help on installing koha

[jackymasibo]

hi guys,
i am trying to install koha on a debian pc and when i run apt get update i
get the following error messages

Err http://ftp.indexdata.dk indexdata/sarge/released Sources
  404  Not Found
Err http://ftp.indexdata.dk indexdata/sarge/released i386 Packages
  404  Not Found
Fetched 197 B in 18s (11 B/s)
W: Failed to fetch
http://ftp.indexdata.dk/debian/dists/indexdata/sarge/released/source/Sources.gz
404  Not Found

W: Failed to fetch
http://ftp.indexdata.dk/debian/dists/indexdata/sarge/released/binary-i386/Packages.gz
404  Not Found

E: Some index files failed to download, they have been ignored, or old ones
used instead.

your help will be highly appreciated.