1. Click the on the toolbar within the content editor to open the Hyperlink Manager.
2. Click the E-mail tab
3. In the Address textbox type in the e-maill address that you want to link to.
4. In the Link Text textbox type in the link's description.
5. Optionally: In the Subject textbox type in the e-mail's subject.
6. Once completed, click the Ok button.

Alternatively, you can add a link to existing text by highlighting the target text and following the above steps.  When using this procedure, Step 4 from above will be done for you.