Looking for certain plug-in or widget

Hello! I am super beginner here! I’m looking for a plug-in or widget EXACTLY like you have at the bottom center of your page that will allow me to create a “Sign Up For Our Newsletter” area to collect email addresses. Any suggestions for what I can use that is EASY to install? How will the addresses be collected… can I specify a certain email address for them all to go to? Here’s the link to what I want, bottom center “Sign Up” area: https://premium.wpmudev.org/join/ Thank you in advance for your help!