If your car is to low to get under... ramps or a jack and jack-stand's (don't be dumb and squeeze your jellybean ass under a 3000 pound piece of metal with nothing supporting it)
A pan to catch the oil, (most auto part stores have them for less than 4 bucks)
A wrench or socket to remove the drain plug and a rag to wipe off hot oil from your hands(or wrap up busted knuckles)
a filter wrench ($10 to $15), channel locks($same) or a screwdriver(if your hard up or too cheap, stab thru the filter and use the leverage to loosen) the filter is going to drain oil when its punctured or loosened so have a container ready (old milk jug with the top removed works good)
don't forget to put your drain plug back in before you start to add oil, always fill up your new filter with oil and lube the seal before installing (I usually fill it up halfway and rotate the filter at an angle to coat all the paper that can be seen thru the big filter hole, if the filter mounts on the side of the motor this is all the oil I will put in the filter, otherwise it will just drain out. If it mounts straight up and down fill it almost full.)
add two quarts and check oil level, continue to check after each quart added until full. Start engine and allow for the oil pressure to come up (15-20 seconds) turn off engine and re-check level.
slam the hood on that puppy... restart engine, blast heat and the music... floor it