Planing is the act of smoothing or thinning wood. It is generally done when the surface of a piece of wood is rough and needs to be flattened down so that it can be used for building furniture. Planing only removes a small part of the wood at a time, usually no more than 1/4-inch off the surface. A table saw is used mainly in cutting large pieces of wood, but it can be set up to be used as a planer as well.
Set the height of the table saw so that the blade is higher than the thickness of the wood you are about to plane, usually about 2 inches higher. It is important that it is higher otherwise you could risk a "kickback," the table saw spitting back the wood towards the cutter at a high velocity.
Set up the the fence so that its distance between the blade is less than 1/2 inch. This measurement between the fence and the blade will be the amount you are planning to plane off your piece of wood. If your piece of wood is very rough then make the distance a little wider so that more wood will be planed off. Don't forget to lock the fence into place.
Turn on the table saw and feed the wood into the blade keeping the side you want to plane off against the fence. Be sure to simultaneously press the wood down and against the fence. Since the blade is spinning at a high speed it has the tendency to lift the wood slightly on the table, so pressing down on the wood will prevent this.
Push the wood through the blade completely before switching off the blade. Do not attempt to pull the wood back out while the blade is still spinning.
Refine your planed surface with sandpaper to smooth down any saw marks.