WordPad cannot save documents as HTML. You could save your documents as .rtf or .docx and use another tool to convert those documents into HTML, but the documents will be cumbersome to maintain and the results are likely to be disappointing.
You'd be much better off finding a real HTML editor or learning HTML and some basic CSS so you can create pages that will look the way you want them to look. The basics of HTML and CSS are very simple and can be learned in just a few hours. All you need is Notepad to create your own pages.