Select your operating system for a guide on how to enable Chinese text input.
It is a good idea to create a keyboard shortcut to switch between input modes. Control + Space is a popular choice.
Go to System Preferences... Keyboard Shortcuts Input SourcesMost people who live in mainland China install a 3rd-party input method. Sogou Pinyin Input is very popular.
The Sogou input method has advantages:The downside is the software must monitor all keystrokes to function, so you need administrator privileges to install it.