Go to http://supportnet.mentor.com and log in.
This will take you to your personal products page. If it is not on a Calibre product page, select a Calibre product (left column).
Click on the Downloads tab.
If the version you want is not the one featured on the page, click on the “Select Release” window arrow.
Then follow the instructions to download.
When you click thru the End User License Agreement (EULA) you will see a page like this from which to begin your downloads. Don't forget to also download and install a set of the latest documentation while you are there.
Once the file is downloaded, move it to the location where you want it to reside.
Execute the file by typing its name on a command line, and follow the instructions.
Once it is installed, set your $CALIBRE_HOME variable to point to the directory location.
For complete instructions, click here.
Check the version of Calibre with $CALIBRE_HOME/bin/calibre –version