An internal link is a link embedded in the text of one web page that links to another page on the site.
To create an internal link, highlight the text within the page which is to serve as link text then select the "insert/edit link" button).

In the "Insert/Edit Link" dialogue window, click on the Internal radio button. You can either search or browse from this window:

To search, click on search and then start typing. Cascade will list out items that you can link to based on your search:

If you don't see what you are looking for, click browse.

Confirm the page selection by selecting the confirm button.
The "Insert/Edit Link" window will reflect the page selection. Select the Insert button.

As always, remember to submit the page.