Well firstly the installer would have told you that the software installed successfully, or not. You would see a McAfee icon next to the system clock which when double-clicked or right-clicked would open SecurityCenter.
Causes of failure can be infection in which case run Stinger and/or Malwarebytes Free from this link: Anti-Spyware/Malware & Hijacker Tools
or.....other security software still installed, in which case remove it. By the way Malwarebytes will prevent McAfee from installing so temporarily uninstall it before trying.
Any problems installing Technical Support is a free phone call away or you can use the Online Chat client, all linked under Useful Links at the top of this page.