How to turn on auto capitalization on my mac?

For Kappy's solution to work, you need to download the free WordService application from the OS X App Store. As part of the download, it installs, but does not enable the service items that you see in Kappy's image. The way the Initial Caps of Sentences service works is that you must select the block of text that you want this to be applied, and then from the Application menu : Services : WordService: Initial Caps of Sentences menu selection, it will then auto-magically provide auto-capitalization of the selected sentences. This is the only mechanism by which this service will work — on selected text.

The WordServices application will be installed into /Applications, and does appear in Launchpad. Its only function, through its Help button is to open Preview with a PDF that describes each installed service item.

There is no auto-capitalization feature in OS X. There is a Fix auto-capitalization check box in Pages '09 : Preferences : Auto-Correction panel. MS Word does not have auto-capitalization enabled by default, but that feature is in the Word Preferences panel.

I followed instruction of WordServices application.

But, it does not change anything.

My MacBook Air is with OS X EI Capitan version 10.11.3

Eileen,

Services usually want some text selected, and WordServices : Initial Caps of Sentences will expect one, or more pre-selected sentences where it can impose auto-capitalization. With selected text, is Pages menu : Services : WordService: Initial Caps of Sentences available in the Services menu?

Did you get WordService from the OS X App Store, or another source?

WordService: Initial Caps of Sentences does not magically turn on auto-capitalization in any application, or the Mac in general.