You DO NOT have to create modules to use DotNetNuke. Repeat that three of four times!
Most likely, you can accomplish more than 80% of what you need using ONLY the Text/HTML module. Just drop modules on the page, and add your HTML. Use the WYSIWYG editor, and you can do a lot without knowing much HTML.
Where you may need some special features, such as blog, forum, announcements, faq, etc., use those modules.
At some point, you'll probably want to explore the world of free and commercial third-party modules. Look in the Marketplace, at snowcovered.com, or scour DotNetNuke related blogs and websites to see what is available.
And ask questions. LOTS of questions!