You can move your shape with text onto the plane by selecting it and dragging it onto the plane using the
Perspective Selection Tool (Shift + V).
To edit your text, simply double-click it to isolate it, and then edit the text.
To pick which plane you want to add you shape to, select it using the following bubble:
The bubble can be found in the top-left of your workspace by default.
In your case you'll want it to look like it does in the image in order to move your shape on the blue colored plane.
Note that you need to have either the
Perspective Grid Tool (Shift + P) or the
Perspective Selection Tool (Shift + V) active to make select a different plane.