Q: How,do,I,upgrade,from,leopard,to,elecapitan

You don't. 

Assuming your Mac supports El Capitan, You need to update to Snow Leopard first.  You can buy Snow Leopard at the following link for $19.99

http://www.apple.com/shop/product/MC573Z/A/mac-os-x-106-snow-leopard

Install Snow Leopard, and update all the way to 10.6.8 to get access to the Mac App Store.

Then you can update to el Capitan  if your Mac supports it.

Macs that support El Capitan:

• MacBook (Early 2015)
• MacBook (Late 2008 Aluminum, or Early 2009 or newer)
• MacBook Pro (Mid/Late 2007 or newer)
• MacBook Air (Late 2008 or newer)
• Mac mini (Early 2009 or newer)
• iMac (Mid 2007 or newer)
• Mac Pro (Early 2008 or newer)
• Xserve (Early 2009)

http://www.apple.com/osx/how-to-upgrade-to-El-Capitan/