Add the Dotdeb repositories to the APT sources. Create a new list file:
nano /etc/apt/sources.list.d/dotdeb.org.list
and add the following lines:
deb http://packages.dotdeb.org squeeze all
deb-src http://packages.dotdeb.org squeeze all
Authenticate the repositories using their public key:
wget -q -O - http://www.dotdeb.org/dotdeb.gpg | sudo apt-key add -
Now you can update the APT cache and install Redis:
apt-get update
apt-get install redis-server
Redis will be started automatically, but you can use the service command to start it manually:
service redis-server start
service redis-server status