On each page, click on the add on icon at the top of the right sidebar to go to the page on concrete5.com where you can assign it to your porject.
Welcome to Performance C5
This site is setup to test addons for concrete5 version 7.
Opt In: I have a review of the Opt In block which works quite as expected but since I find these things offensive I removed it.
Under Construction: This really works well but when you install it routes everybody to a designated page no matter what you click on. Not good on a live site.