Ive downloaded OS X EL Capitan but had to halt the installation who do complete installation

Hey martiniqu,
From what you describe, it sounds like you have downloaded OS X El Capitan but didn't install it. That is an easy next step, just open up LaunchPad and look though the pages of Apps to for OS X El Capitan. You can also look in the Application folder of your Mac as well. For more details on using LaunchPad, take a look at the article below.
Mac Basics: Launchpad is the fast way to find and open your apps
https://support.apple.com/en-us/HT202635
Take it easy