Measure the lattice panel and mark it along both edges where you will cut it to get the length and width you desire. Use a large drywall square to draw a line from the edge, marking each intersection in the lattice where you need to cut it.
Locate the height adjustment wheel underneath your table saw on the side of the saw's body. Twist the small knob in its center counterclockwise to release it. Turn the large wheel clockwise to raise the blade as high as possible.
Unplug the saw. Remove the throat plate; wedge a piece of wood behind the blade to keep it from turning. Use a wrench to turn the arbor nut in the center of the blade counterclockwise to remove it. Lift the blade off the arbor spindle. Slip a fine-tooth blade onto the spindle, with the teeth points angled toward the front of the saw. Reinstall the arbor nut and throat plate.
Reset the height of the blade to 3/4 inch so that more of the saw's teeth contact the lattice for a smoother cut. Adjust the saw's fence to the first dimension you want to cut. Plug the saw in.
Start the saw and pass the lattice through the blade, with one edge against the fence. Keep an eye on the marks you made to ensure that the lattice is not "wracking" or twisting and that the saw is making cuts where you want them. The blade should pass through each mark.
Push the lattice on through the blade and turn the saw off. Allow the blade to stop before retrieving the lattice. Reset the fence to cut the second dimension of your lattice and repeat the cutting process.