Place them in a cluster around each other like this.

Now choose your bunch of white flowers. Add glue to the bottom of this bunch and press down and add a pinch or sheet moss arounf it as you press around them so that they will stand up straight. If they lean add a small drop of glue and press more moss around to make them stand straight up.

It should look like this

Now take your small yellow flower bunch and add glue and press them down. Always remember, smaller flowers should be in the front and larger flowers look better in the back.

Add them as shown in the picture.