To create a link to an internal page, use the tab 'Page' and then click the desired page in the pagetree (1) as, for example, it is displayed below. Links to internal pages will automatically open in the same window, but you can force a page open in new window/tab by clicking the target dropdown (2) and choose 'New window'. (4.4.2)
You can link to an email address, by selecting the tab 'Email'. All link options has a 'Title' field (1) where you can add information about what the link does.This information will be shown when the visitor hover the link in frontend. Add the email address in the 'Email address* field (2) and apply with 'Set link'. (4.4.6)
To create this type of anchor link, mark the text in the text area and click the link icon (As shown in the first section). Below the Page tab, instead of clicking a page title, you click the small arrow icon on the left hand side of the page title. This will list all available content elements on that page, where you can then select desired anchor content. When using this function, it is important that the content on the page is divided in to separate elements, and that they have a header. Elements without a header will just say 'No title', and it will be impossible to know which element/section to link to. (4.4.7)