There are a couple of ways to add text boxes to your page or cover.
Click on the Text palette shown in the left vertical toolbar.
When the Text menu opens, you'll notice there is a helpful reminder up on top to "click or drag text below to place on the page". It's really that simple! Choose what type of text you'd like to add to your page (Headline, Subhead, Body Copy or Caption) depending on what your layout calls for -- then either click or drag onto your page.
When a user clicks on one of the text styles listed, a text box will appear on your page. Double-click text to edit and you're on your way.
When a user drags a text box onto their page, the exact same thing will happen. A text box will appear, double-click to edit.
Change font style, color, size, spacing...all from the contextual menus that appear.
Need to add another text box? Copy and paste the box you've already dragged on or go back to the Text menu and choose the style that suits your need best.
Need to delete a text box? Select the text box and when the menu appears, use the trash icon found at the bottom of the vertical tool panel.