Step 1 - open a browser window and copy the url you want to use. In this tutorial, I will use the Apple site. The complete url is http://www.apple.com.
Step 2 - type your text in the body of the email. In this example, I type "Click Here" to go to the Apple website.
Step 3 - highlight the text for the link, in this example Click Here will be highlighted. Once you highlight text, this icon will become available:
Step 4 - clink this icon and paste the url in the box "Link URL" and click Insert.
Here is the finished sentence: Click Here to go to the website.