To install Joomla via Softaculous please follow these steps.
1. Login to your cPanel account http://yourdomain.com/cpanel
2. Scroll down to Software/Services section and click Softaculous.
3. In Softaculous page, hover on Joomla and click Install.
4. In the Installation Wizard just fill out the installation details and don’t forget to enter an email where the details will be sent.
5. Click Install.
Once done, clear your browser's cache and you should be able to view your joomla based website at yourdomain.com