When you export your Hype document, you have the option of exporting an .html file. This HTML file contains a small snippet of code that loads your Hype document in an area the size of your 'Document Size' set for your file. If you want to modify that exported .html file, you'll need an HTML editor. There are many applications that edit HTML files, but here are a few of our favorites:
For more information about what HTML is, head on over to Wikipedia.