There are two different things to consider with "grounding" your monitor
1) When installed into your cabinet the frame of the monitor should be grounded to the cabinet's field ground (the middle prong from your outlet). This is usually a shared ground to anything metal in your cabinet.
2) Discharging the monitor by grounding it is really only needed if you are going to disassemble it, wash it, or otherwise manhandle it. If you are just putting it in the cabinet, there's really no need. Regardless, to discharge the monitor you need to ground the anode in the tube to the aquadag (black paint on back of tube) of the monitor. You can take an alligator clip jumper wire and clip one end to the frame of the monitor. Clip the other end to the shaft of a metal flat blade screwdriver. Slide the blade of the screwdriver under the anode cup (the suction cup thingy on the tube with the red wire coming out of it). Wait a couple of seconds and you're done. You may or may not here a "snap". This is a temporary deal. E.g. you don't leave this grounded. If you do this wrong and then handle the tube you may get zapped. It won't kill you it will just more or less piss you off.
Good luck.