How to download OS X El Capitan - Apple Support includes a d/l link for El Cap.

Apple doesn't want you to be behind the times, so they make it difficult to find back OS versions. Searching the App Store isn't the answer; you've got to do a Google search.

The new Great Equalizer is the SEND button.

In Memory of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire