Some quick notes on custom code.

There are three parts to this code. A "CSS Code", a "JavaScript Code", and a "HTML Code". They will be placed in different areas. (More on that below.) You are given an input box for the color of the popup. You'll need to put your HEX code for the color of your choice in there. You will enter your password in the "Set Password" box. It is case-sensitive, so make sure you write it down. For the "Password Required Text" box, this is where you will give your instructions. You can say, "Password Require for Access", etc. 

-For the CSS Code --> This entire code will be placed in the settings of the landing page you are using it on. To access that location, click the "settings" tab at the top. Once there, click "custom code". Paste the CSS code in the box that says "CSS Code". Then click the "Save" button to save changes. 

-For the JavaScript Code --> You'll access this the same way you did the CSS, but you'll paste this code into the "JavaScript Code" box. Remember to hit Save. 

-For the HTML Code --> This code will get placed in a "Custom Code" Block anywhere on your page. You won't be able to see the code on the page, but the "empty" block will still be there, so place it somewhere that you don't mind a little extra space.