Add a new linked page
From the page you're going to add the link to:
click the Edit this page icon,
click the line you want to add the link on, then either:
add the text between double square brackets [[link to the page to be created]]. Once saved, the text entered between brackets will be transformed into a link to a new empty page
or click the Insert/Edit Wiki Link icon in the editor to indicate the name of the new page to be created.