i can't download el capitan

If you are running 10.6 as your profile shows, macjack's link should work.

Check to make sure your applications are compatible. PowerPC applications are no longer supported after 10.6.

Application Compatibility

Applications Compatibility (2)

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.

If your Mac is capable of running High Sierra, El Capitan will not be available from the AppStore. If not try this link:

get El Capitan from the App Store