You need to use a balancer puller/installer, other wise very easy to do, make sure you torque it back down to spec. Put the car in gear so the motor will not turn over....
you are going need to rent/buy a damper puller. first remove the bolts that hold on the crank pulley. then remove the bolt that holds the damper(remember to remove the washer behind the bolt). then use the damper puller to pull the damper away from them block. like rick91gt said make sure the motor is in gear.
Stock replacement balancers run around $100, you could get a SFI approved Pioneer for around $180 or a Romac for around $240 check out www.adperformance.com