Here's an example. If I wanted to make this (Hello, how are you?) into a link, I would
1) Type: Hello, how are you? wherever I want the link to be.
2) Select (highlight) this text that you want to turn into a link.
3) Hover over the infinity symbol in the edit box above all the text. It will say something like "add link." Click this while the text is highlighted below.
4) Add the url (http://www.whateveritis.com) and click save