The property you're looking for is "InnerText". So, for example, on a hyperlink like:
HtmlHyperlink target = new HtmlHyperlink();
target.SearchProperties[<search property>] = <value>;
string myText = target.InnerText;
You can extrapolate this to just read all of the text on the page by selecting the outer container of the page and getting the InnerText of it, then parse through the string for what you want, but I've found it a lot simpler if you work in the most focused object.