Underneath a modern and user-friendly interface, Scribus supports professional publishing features, such as color separations, CMYK and Spot Color support, ICC color management, and versatile PDF creation.
Install scribus on ubuntu
Open the terminal and run the following commands
sudo apt-add-repository ppa:scribus/ppa
sudo apt-get update
sudo apt-get install scribus-trunk
If you want to know how to use scribus you have to check their documentation