Do you have a specific requirement to run cmake version 2.8.9? Version 2.8.7 is available from the repositories and can be installed by running the command
sudo apt-get install cmake
If you must compile a version yourself you will need to run the make install command as
sudo make install as your application needs permissions to install itself into the filesystem.
To check for cmake files after compilation, run the command
sudo updatedb and then
cmake from the command line, without any options, specified and you should get some output on using various command flags if the application compiled correctly.
Update: rolled up previous comments into this answer.