Hi Heather! You can use Notepad to edit HTML files, it's enough to edit the texts for this example. Unfortunately, I can't see your example, because it's located on your computer, not on a server. You can try to publish it in Storyline and share the Review link with me, so I can see how does it look like on your end.
Here is the description of how to edit the example -
Inside the downloaded files you will find a folder called 'Web Object'. Inside this folder you will find an index.html file where you can see all the information that is shown on the right panel in the demo. Edit this information and you will see how easily the tabs adapt to it and make space for a larger amount of text or additional images.
Once you put the file on your computer you will have to change the location for the 'Web Object' folder. To do so - click with the right mouse click on the Web object and select Web Object/Edit. There you can select the small folder icon and locate the folder on your computer. Now everything should work perfectly!