Lay your 15-inch oak boards horizontal and parallel to each other, so their outside edges are 23 inches apart. Counter sink two holes in each end of the 22-inch boards to a depth of 1/4-inch, spaced 1 inch away from the ends. Screw each 22-inch board perpendicular to a 15-inch board at its center, or 7.5 inches in from the end. Leave 1/2 inch on both edges of the 22-inch boards. Repeat this process with your last 22-inch board and the other 15-inch boards.
Stand both sets of 15-inch boards upright so the 22-inch boards are between them, parallel and 22 inches apart. Counter sink two holes at each end of the 23-inch boards just as you did for the 22-inch boards. Screw the 23-inch boards to the 22-inch boards so you have a 23-inch-by-23-inch square formed by the 1/2-inch oak boards, held together by the 15-inch boards. The 15-inch boards are your table legs. Counter sink 1/4-inch deep holes for all following screws.
Screw the plywood to the ends of the 15-inch boards so the plywood's 23-inch sides are 1 3/4-inches from the 15-inch boards.
Screw each of your 2-by-23-inch oak boards to the 23-inch sides of the plywood. The 23-inch oak boards should be parallel to the plywood, and 1/2-inch above the top edge of the plywood. The ends of the oak board should be flush with the edges of the plywood.
Screw your 36-inch board to the 34 1/2-inch edge of the plywood. The ends should be flush with the 23-inch oak boards, and the 36-inch oak board should be 1/2-inch above the plywood. The function of the boards surrounding the plywood is to hold the granite tiles in place.
Sand down your entire project with your medium-grade sandpaper, and then with your fine-grade sandpaper. Wipe the project down with a tack cloth, apply the wood stain, and let dry according to instructions. Set your six granite tiles in the table after the stain is dry.