How do I upgrade from 10.75 to Sierra?
How do I upgrade from 10.75 to Sierra?
VIN, iMac (21.5-inch Mid 2010)
How do I upgrade from 10.75 to Sierra?
VIN, iMac (21.5-inch Mid 2010)
Check to make sure your applications are compatible.
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 you mean Sierra, you can upgrade directly. If needed, use the link below.
If you mean High Sierra, you need to download El Capitan or Sierra first.
(155082)
How do I upgrade from 10.75 to Sierra?