Looks like stucco on rebar to me ... but I'm certainly no expert!

It is white painted or white tinted stucco.
A footing is built of concrete , metal rebar is embedded and concrete block is built up with concrete backfilling the concrete voids.

For the fire place a firebox is installed along with a flue. It becomes more complicated if you are installing a gas fireplace vs. a wood fireplace.

It's really not a DIY'er project if you include the fireplace.
If you are just considering building the circular seating area without the fireplace then I think that is in the realm of a DIY'er project.

Thanks for the replies! I was just wanting to make the seating part.

Could you help me with some instructions? Could this be put on concrete?
I was going to try the put a basic DIY fire pit in the middle...not like the one in the picture.

I will try to get a picture of the area I am trying to build it in later tonight!

Thanks

Whether you build the surround out of stone or stucco, the substructure will usually be made out of Concrete Masonry Units.
Best to pick up a library book on laying CMU or hire a professional. It requires some skill , a variety of tools and past experience will prove helpful .
From

So your saying your saying what I am trying to accomplish won't work? You can't build on existing concrete?

What about just pavers you can buy from home depot?

{{gwi:11610}}

You can probably plunk down some pavers from Home Depot, but you won't achieve the look that is in that book/ photo.

If I were given the task to design a seating ring with that existing slab I would want to do some research first to determine the slab thickness and how it was reinforced.

If I were to determine that the slab was properly reinforced and had a min. thickness of about 4 inches I would feel confident in designing the seating portion ontop of the slab but the back rest portion would be built with a footing on the outside perimeter of the slab.