You can install Joomla on your account via the automatic script installation system - Softaculous. Here is the way of installing Joomla from Softaculous:

cPanel --> Softaculous --> Portals/CMS --> Joomla --> Install

The other way you can install Joomla on your web hosting account is to install in manually. If you want to perform a manual Joomla installation and you do not know how exactly to do it, you can follow our detailed tutorial here:

http://www.siteground.com/tutorials/joomla/joomla_manual_installation.htm