Below is the step-by-step guide to password protect a page/post in WordPress.
Step 1 – Log in to word press admin
Log in to www.yourdomainname.com.au/wp-admin
Step 2 – Navigate to post/page section
Step 3 – Add new page or edit existing page
Step 4 – Set visibility status to password protected
Find the Visibility label under the Publish metabox. Click edit and change visibility to password protected. Enter new password and click OK. Publish / Update the page.
Step 5 – Test the page.
Click on view page. If everything went well, your page will ask you to enter a password. Enter the password which you selected and see if it gives you access.
Password protecting a page is really easy in WordPress.