Installing GnuCash is simple. There are two ways to manage this task: via the graphical installation tool or via the command line. To install via the graphical installation open up your installer (Yumex, Synaptic, rpmdrake), do a search for "gnucash", select the results, and click apply. To install via the command line you will issue one of the following commands (depending upon your distribution):
sudo apt-get install gnucash
Once GnuCash is installed you will find it located in your desktops' Office menu. If you do not find a menu entry for GnuCash you can open up your desktops' "Run Command" window (from the main menu) and issue the command gnucash to start the application.