Adding hyperlinks is easy.  You just highlight the text, and then go into the window of a browser that is showing the webpage you want to link and highlight the link (holding down on the left mouse button and dragging it across the link) and then type <Ctrl> c.   That means you hold down on the <Ctrl> key and hit 'c' at the same time.   This copies the link into your clipboard.  Then you go into the window that is asking for your link and hit <Ctlr> v, which pastes it into the link.  If you go to the edit HTML mode, you'll notice that the composing window has some strange text in it, which is html.  When you preview it, you'll see the text is highlighted which means than anyone can click on it and be taken to your link.