To add your own HTML Source Code to any page on your site, you will need to do the following: 

Click on "List Pages" and then click on any free form page from your site, where you would like to add the source code to.  Next, click on the "Edit Raw HTML" link above the editor box and place your cursor at the end of the very last line of the existing text and press the enter key on your keyboard to move the cursor down to a new line. 

Next, type in or copy and paste the necessary codes into the editor and click on "Process Page Update" at the bottom of the page.