A Punnett square would help here.
Let's say (R) is dominant red and (r) is recessive red, aka yellow.
You start with F1 hybrid flowers that are all (Rr) - these are all orange. So when they reproduce, both parents are (Rr). When you create a Punnett square, you'll see that the results for the F2 generation are (RR), (rr), and (Rr) twice.
(RR) is red, (rr) is yellow, and (Rr) is orange, just like the F1 generation.