making a link is a simple question of HTML.
If you are not familiar with HTML, you should visit some reference sites and tutorials.
The base of an HTML link tag is below, but there are optional attributes you can add. Just edit your text widget to add the proper HTL code like below, replacing LinkURL by the full url of the link to be used
<a href=”LinkURL“>Your text</a>
reference sites below
http://webdevrefinery.com/forums/topic/6-just-starting-htmlcss/
https://developer.mozilla.org/en-US/docs/Web/HTML
https://developer.mozilla.org/en-US/docs/Web/CSS