Begin by eliminating ignition problems first: Be sure your kill switch is in the "run" position. ( I know, it sounds stupid, but you would be amazed how many bike owners will hop on after a riding break and leave the switch in the "off" position)
Next, using an old plug and leaving the installed plugs in place, unplug the cap to one of the outboard plug wires; either the #1 or the #4 and plug the old loose plug into the cap. Insure that the threaded portion of the plug is resting on metal and hit the starter button. You should see a fat blue spark at the loose plug electrode.
No spark? You have an ignition problem which will require more troubleshooting, but I am assuming when you parked it a year ago it ran, thus I will jump straight to what I think is the problem. Re install the plug cap.
Obtain some spray start and following the instructions, spray into the the throat of the carb, or into the air box. Immediately attempt to start. If it coughs/farts/sputters, you are in luck. Your ignition system is probably OK. You then need to move onto the fuel delivery system.
These bikes do not take well to long term storage as the remaining fuel will separate with the combustibles evaporating leaving a dark shellac-type residue. This can cause blockage of the very small main and pilot jets which will result in poor performance or a no-start condition. A first step is to unscrew the drain screw at each carb bowl and drain the contents followed by a flush with fresh fuel from the tank. If no debris, water, or gook (a technical term) is noticed, attempt to start the bike again. If it starts, but runs rough, I would recommend for you to pour some SeaFoam into the tank and run the engine http://www.walmart.com/ip/Sea-Foam-Motor-Treatment-16-oz/16664932
. This will clean the entire fuel system and may take a couple of treatments.
In the event you did not get the engine to come to life, you may have to pull the carbs to clean them thoroughly. A good instructional video is found on youtube here: http://www.youtube.com/watch?v=AXoDX1RzBJ4