WHMCS Download :
1. Visit http://download.whmcs.com/
2. Click the download under the latest full stable release. You will need login credentials for download and a license for active installation. You can purchase these from the WHMCS website.
WHMCS Installation :
1. Unzip the downloaded whmcs_vXX file on your computer.
2. Inside the whmcs folder, find the file configuration.php.new and rename it to: configuration.php
3. Connect via FTP to your web hosting and upload the whmcs folder. You can rename this whmcs folder as whatever you like
4. To run the installation process, visit the installation script at http://www.YOURDOMAINHERE.com/whmcs/install/install.php
5. Follow the prompts on screen to complete the installation. This involves accepting the terms and conditions, system requirement checks, file permissions (please see the file permission details below.), a license key (available under Services → License and services → View Details with Active status), creating a database and entering administrator information
Required file & folders permissions (unless your php is suPHP or PHPSuExec):
/configuration.php CHMOD 644 Writeable
/attachments CHMOD 777 Writeable
/downloads CHMOD 777 Writeable
/templates_c CHMOD 777 Writeable
/configuration.php CHMOD 400 READABLE*
*If using DSO as your php handler, you must use 644 permissions.
Post Installation Steps
1. Delete the install directory from your web server
2. It is advisable to move the attachments, downloads & templates_c directories (which need to be writeable for WHMCS to function) out of the publically accessible folder tree. Instructions on how to do this can be found in WHMCS documentation: http://docs.whmcs.com/Further_Security_Steps
3. Setup a cron job in your control panel to run using the following command once per day:
php -q /home/tptp1762/public_html/whmcs/admin/cron.php