WebDesign provides a convert from HTML code to XHTML code feature. This conversion feature will do its best to convert an HTML document into a proper XHTML document. There are, however, areas where this conversion feature can not meet the XHTML standards. This includes fixing badly formatted HTML or ensuring all attributed values are quoted. You will have to fix these things manually.
To convert your document from HTML to XHTML select this option from the HTML Tools menu. A new window will open allowing you to set the options that WebDesign should use when converting your document. Your document type will automatically be converted from HTML to XHTML mode.