In the Text panel, enter your desired text, choose from a variety of fonts, as well as change the Size and Color. You can choose a fixed width for a text box by toggling Wrap Text, which can be done by number of characters or width. You can also set the alignment and whether or not the object faces the camera. When that is toggled on, the text always looks at you no matter which way you view the space, which can be very nice sometimes, especially in augmented and virtual reality.
In the Image panel, choose the file from your computer, change the size and toggle on/off face camera.
3D arrows appear when selecting a text/image object, and are really great for positioning in the space. The green arrow goes in the vertical direction, the red arrow goes in the horizontal direction, and the blue arrow goes in the depth direction. There's also this middle point where you can click and then just drag it wherever you'd like. If you ever get lost where your text/image is now super far away and you can't find it, you can go down to Position in the text/image panel and hit the small minus buttons (to the right of the position numbers), and it'll recenter it for you.
Similar to Maps, Animate between steps should be toggled on if you'd like to have two different steps with the same text/image, but in two different positions.