Did you download InstallMacOSX.dmg.
Did you open that to get the InstallMacOSX.pkg.
Did you open that and got an installation window.
Did you know that does not install Mac OS X El Capitan.
After all it only took 2 minutes to do and said it would take 7MBs of Disk space.
No operating system only takes 7MBs of Disk space and two minutes to install.
What is actually happening is the Install OS X El Capitan.app is being created in your Application folder.
Have a look, double-click it to start the installation of Mac OS X El Capitan.
Should take about 30 minutes.