trying to upgrade yosemite to el capitan system 2009 wont support sierra

Upgrade to OS X El Capitan - https://support.apple.com/HT206886 - "OS X El Capitan remains available for Mac computers that can't upgrade to macOS Sierra, or that need to upgrade to El Capitan first."

Check to make sure your applications are compatible.

Application Compatibility

El Capitan 10.11 Compatibility information

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.