Now that your greenery is framed in for height, length and width, you simply fill in the rest.
For once, I'm going to encourage you to keep the design a little flattened. You will probably have these hanging on both sides of the aisle and you want to be sure that the aisle is clear enough to allow two people to pass escorted down the aisle at a time without knocking into the flower arrangements.
(You need to keep in mind your dress width as well!)
I continue to cut shorter fronds and quickly fill in the foam, creating a base of greenery.
I keep the leather cut shorter when working near the foam itself.
As I fill in the center, begin angling the greens, first at a 45 degree from the back pieces of leather until the ones in the direct center are sticking straight forward at a 90 degree angle.
Don't worry about being too perfect. Part of the charm is that the greenery follows the flow and curve of the natural pieces.
It doesn't take long to fill in and lightly cover the foam.