If you are on a wood floor don't use any mortar. I used a hardwood moulding around the area I wanted the bricks to lay in. Then laid Paver bricks, they have no holes, tightly together. I drilled recessed holes for screws and used Wood Buttons to hide the screws. I attached the one long side and one end moulding and laid the bricks so I could tell how long the moulding was going to have to be.
Bricks are notoriuosly different sizes.
Lift the moulding and cut the two pieces to length, replace them and finish laying your brick and apply the other two moulding pieces. I believe this would be easier for you since you have no masonry experience. If I can be of further help just ring me up. Last year I re-shingled my house in Tampa, Fl. It had an old chimney that was no longer in use, so I removed it.