You can add working HTML links to a TextEdit file.
Select the text you want to use for the web link.
Choose Edit > Add Link.
Type or paste the Internet address (the complete URL) in the “Link destination” field, and then click OK.
Be sure to use the correct form (for example, http://www.apple.com). You can click the link to be sure it works.
You can also copy a link from another document (such as a webpage or an email message) and paste it into a TextEdit document. When you save the text file, the link remains active.