Text, pictures, and other content is added to a site by dragging "elements" from the left side of the screen and then dropping them to a page. How do you drag one of these elements?
Scroll your mouse over an element. Like the Text element, for example:
Then left-click on the element with your mouse and drag it to the page. Once you've found where you'd like to place it, release the left button on the mouse and the element will be dropped. Now you can edit this element to add your content (which is text in this case).
To learn more about using the editor and building a site, take a look at our Beginner's Guide. In the amount of time it would take you to make a pot of coffee and drink it, you can learn all the basics of putting together a great site. See the Beginner's Guide here: