Closing off front opening?

I’d like to close off my front opening and am curious about how to support the fire brick over the opening? Do I just lay a piece of angle iron over the lower support bricks and brick right over it? And if so does the iron need to be anchored into the arch on both sides or does it just set there and float? Any help would be great.

I built a wood arch and used it as a support for the firebricks. I used thin pieces of cardboard to create a separation from the firebricks and the wood arch to allow for easy removal of the form once the mortar was dried on the arch.