I could think of a couple of ways to do this, but they would likely be beyond the skill set of your handyman. The problem is that, if you want it to look decent, you don't want someone doing it who is learning on the job. What is the possibility of getting someone more experienced to do this for you?

If you gave a Menards near you, they have diy fire pits and benches. They are pre-cut stone. We thought they were decent prices.

http://www.menards.com/main/building-materials/landscaping-materials/the-project-store/landscaping-projects/no-cut-block-projects/c-13093.htm

I'd simply go to Home Depot and buy the pre-made kits for this. It really isn't too hard on this decision.

Permit required? (You said corner of back yard.)

You might get a lot more advice on the Garden Forum rather than the Home Forum. I think the Garden Forum has a gardening with stone section. Click on GardenWeb topics at the top left of this page and follow the links.