Click directly on the text in the preview and drag it to where you want it. Ideally, place it where there's nothing else on the image yet.
Using the two tabs "Artist name" and "Song title", you can set the font, size, color, and shadow separately for each text. You can choose from many fonts. With the selection above the preview, you can check how the result looks in each of the formats.
If a text is very long, it automatically wraps to the next line and stays within the image.