You can add hyperlinks by using the toolbar Insert/edit link button when in the Visual editor. Tip, a quick way to add a hyperlink to a piece of selected text is to paste (Ctrl+V) the URL, whilst the text is highlighted.
WordPress 4.3 introduces an easy way to preview links.
Just by clicking on a link in the Visual editor, a simple inline toolbar displays the URL in full, along with buttons to Edit or Remove it. This avoids opening the Insert/edit link modal window accessed from the toolbar.