After Darnell rotates the first rectangle (the one in Quadrant III) 90 degrees clockwise into Quadrant II, the next step is to translate the now-rotated rectangle to align it with the second rectangle in Quadrant I.
To find the correct translation, he needs to determine the coordinates of the corners of the newly rotated rectangle to see how far they are from the corresponding corners of the second rectangle. After calculating, he can apply the translation to get them to be congruent and in the same position as the second rectangle.
Thus, the answer to your question is:
Translate the rotated rectangle to align with the second rectangle.