How to Install Password Add On:
Step 1: Go to /wp-admin
Step 2: Go to Plugins> Add New
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Step 3: Click – Upload Plugin
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Step 4: Choose file and click “Install Now”
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Step 5: Click on “Activate this plugin”
Note: You need to go to DSP Admin>Settings- Password and turn it “On” to see this add on your registration page.
Also see link: http://www.wpdating.com/documentation/how-to-use-password-add-on-feature/