To verify your email, first, you need to set your email on your Plutonium account.
To do this, click your profile in the top right corner on the forum, then click "Edit Profile". Here, on the right side, click "Change Email" and enter the email you want to use and your current password, then click "Submit".
Shortly after, you will receive an email from Plutonium with a link that you must click to verify your email. Click it and you're good to go!