Create a Blog Count Plugin To Work With Upfront

Hello.

I want to create a plugin/widget to display the number of sites created in the network. I know that the code needed is:

<?php
  $blog_count = get_blog_count();
  echo 'There are currently '.$blog_count.' blogs running on this server.';
?>

But I need to create a widget to be able to use it.

How can I create that widget to be inserted in upfront themes?

Thank you!