Step 1:
This paper is 12x12 centimeters and yellow on one side.
Fold in half

Step 8:
Prefold.

Step 6:
Press flat and repeat step 5 and 6 over this purple line.

Step 12:
Bend and glue to the backside of the flower

Step 11:
Pull the four inner petals upwards.

Step 10:
Fold the corners straight upwards.

Step 9:
Fold the corners to the center.

Step 5:
Fold over the purple line

Step 7:
Fold the yellow part in half

Step 3:
Fold in half

Step 2:
Fold over this line.

Step 4:
Fold the white part in half, then fold over the line below

Done!
This is a video tutorial for folding the ring: