Once you receive the welcome email from LastPass, click on the Activate LastPass button in the email.

Fill in the activation code from the email and make sure that your email address is correct.
Make sure you create a strong master password - the Strength Meter will show you how your are doing.
Here are some suggestions on creating a strong password that you can remember.

When successful, you will receive a confirmation.

Install the LastPass Authenticator App on your mobile device. You will be able to find this in either Apple App Store or Google Play Store.

Go ahead and install LastPass Password Manager extension(s) in the browser(s) you use by clicking on the Install LastPass button. It will take you to the appropiate extension install for the browser you are using to enable your account or you can copy the links below in the appropriate browser.

Firefox: https://addons.mozilla.org/en-CA/firefox/addon/lastpass-password-manager/
Chrome: https://chromewebstore.google.com/detail/lastpass-free-password-ma/hdokiejnpimakedhajhdlcegeplioahd
Edge: https://microsoftedge.microsoft.com/addons/detail/lastpass-free-password-m/bbcinlkgjjkejfdpemiealijmmooekmp