Turn the guide on the top of your table saw to the angle you prefer. A table saw's adjustable guide often looks like a protractor with angles marked around the edge. Loosen the knob on the guide to allow you to turn it, set it to the correct angle and tighten the knob back down again.
Place the piece of wood on the saw's table and press it firmly against the guide. Adjust the depth of the blade so that its top sits roughly an inch above the top of the wood.
Turn on the saw and while holding the piece of wood squarely against the guide, push the guide toward the spinning blade in a smooth, steady manner. Allow the spinning blade to do the work for you; don't force the wood in quickly or the blade may bind and splinter the wood.
Ask an assistant, especially if the piece of wood is large, to catch the two halves after you have pushed the wood through the blade. Request that the assistant does not pull the wood through the blade; he should allow the pieces to come toward him.