There is no direct way to screen lock your Mac without any third party software.
A workaround would be to set your Mac to screenave or sleep quickly, and make your Mac ask for a password when it to comes back. This setting can be accessed in the Security panel of System Preferences.
There is. Open Keychain Access, go to its Preferences/General, and check the box that says "Show status in menubar". From the new lock icon in your menubar, select "Lock Screen".
There is. Open Keychain Access, go to its Preferences/General, and check the box that says "Show status in menubar". From the new lock icon in your menubar, select "Lock Screen".
There is. Open Keychain Access, go to its Preferences/General, and check the box that says "Show status in menubar". From the new lock icon in your menubar, select "Lock Screen".