Measure the table surface and decide how large to make your wood surface. It is best if the wood surface overlaps the edges of the existing table by at least four inches to hide the existing table.
Cut your wood surface to the desired dimensions with a table saw or hand saw.
Sand the edges and surfaces of the wood with either a power sander or sanding block to create smooth edges and a smooth surface.
Place the wood surface on the existing table, measuring to ensure it is centered, and clamp it to the surface with C clamps to keep it from moving.
Drill wood screws through the existing table and into the table surface at each corner. Make sure the screws are shorter than the combined thickness of the table and wood surface to ensure that they do not break the surface when screwed into place.