You can create links by copying and pasting existing links the same way you copy and paste text and images:
For instance, if you want to paste the link onto a particular word, select the word.
You can also copy text from a file, and paste it as a URL. For example, if you have a file that contains a URL that is listed as text, such as http://www.fred.com/index.html, you can copy the text, and then follow steps 3-4 above to paste that text as a URL.