How do you upgrade from OS X 10.95 to OS XEL CAPITAN

You cannot. El Capitan is no longer available since the release of Sierra, unless you have a model that cannot run Sierra:

The official list of Macs compatible with macOS Sierra:

2010 or Later

• MacBook Air
• MacBook Pro
• Mac mini
• Mac Pro

Late 2009 or Later

• MacBook
• iMac

If your computer isn't compatible with Sierra, back up your data,check your applications for compatibility, click here, and download El Capitan from the Mac App Store. If it is, you'll need to go to one which isn't or is running 10.6.8, download the installer with your Apple ID, and move it to your Mac.

(146213)

El Capitan 10.11 Compatibility information

macOS Sierra 10.12: Compatible Apps

Also check to make sure there is a compatible driver for your printer.

Do a backup before installing, preferable 2 backups on 2 different drives.