This is the "Insert/edit link" button.

If you click the arrow next to the icon, a dropdown of options will appear with the types of links you can add.

A page link will direct you to a specific page within the same website.

A file link will direct you to a downloadable or viewable file, such as a PDF, document, or image.

A website link will direct you to an external website outside of the current domain.

An email link will open a default email application to send a message to a specified email address.

A phone link will bring the user to a phone call to a specified telephone number on compatible devices.

An SMS link will open the user’s messaging application to send a text message to a specified phone number.

If you click the link icon, this will come up:

This popup includes several configuration options:

• Text to Display – The visible text that the hyperlink will be attached to.

• Style – Controls how the link appears. These styles are similar to those found under the "Format menu", but they apply specifically to links. The available styles are site-specific and are set up by the developer.

If you click “Other link settings,” an additional settings window will open.

This is will allow you to further customize the link.

Under URL, next to the button that says “Add”, you can copy and paste a website URL. If you want to add a very specific link, click “Add”. This is what you should see:

From here, you can choose what type of link you want. They are the same options as in the dropdown. 
The first option is Page:

After clicking on page, you will be able to choose what same website page you want to link to. 

Underneath Pages, you will see apps. These are site specific. The example we have is blog.

After clicking on the app, you will see the general pages for that app. You could also choose the category, specific posts (this is blog specific), and tags.

The next option is File.

Underfile, you can click on the folder the file you want is in and then on the file.

The next option is website

Here, you can paste the website link and set the URL.

The next link option is an Email link

Here, you can paste a link to an email address

The next link option is a phone or text link

Here, you can paste a phone or text link.

The next button is the remove link. Highlight the text that you want to remove the link from and click the button.