You'll line up a white square in one of the corners, and a yellow square in the opposite corner from that. If you do happen to start with a 5.5 square please cut the white and yellow squares down to 2.5".
I found it helpful to make a line from corner to corner of the small squares so that I could sew a straight line.
Once you have each square sewn on, measure 1/2 inch from the line you sewed and cut the corners off.
It will look like this. I generally press my seams toward the darkest fabric. I do not press seams open, just to one side.
Once you have 4 of these made you will sew two together. The yellows go towards the center to form the center of the flower.
At this point, I usually press the seams in opposite directions, can you see that in the picture? That's probably common knowledge, but I didn't know it at first. It helps to get the middle seam lined up a little better.
Et, voila! The finished square. I didn't measure the final square but from the final picture here it looks like about 12.5? So, I would consider this one a pink flower because I used prints that were mostly pink. If you don't have enough of the color you'd like to do, let me know and I'm happy to send some out! 
This blue one was my first try, the pic is a little dark here, but you get the idea. You don't have to pick a pastel, any color is good. Thank you!
