Welcome Kymco Owners!
Remove the center cover and reach in on the left side (looking to the back of the scooter) of the engine. There you will find a black wire and a sparkplugcap going into the cylinderhead of the engine. pull out the sparkplugcap and use the onboard tools to remove the sparkplug.
Go on Amazon and type in kymco performance plugs, order it, 1 comes, might not be the yellow one, BOTH are the same, and work great. Its an equal to the plug it came with, as the heat level=ok.
FYI....Please note that removing the center cover is not as easy as removing the two philips head screws at the bottom of the cover. To safely remove the center cover, you need to remove the seat/bucket and then you can access the tabs that lock the center cover in place. If you try to remove the center cover without removing the seat/bucket, I can almost guarantee that you will snap off several of the plastic tabs that lock it into place. Removing the seat/bucket will also make it easier to access the spark plug. Also, threading in the new spark plug is not easy because the spark plug hole is set in so deep. The best way to thread the new plug into the spark plug hole is to attach a short piece of fuel hose to the threads on top of the plug and then thread it into the hole. It may take a few attempts to thread it in properly. Just be sure not to cross thread it.
[veryN o o o o....The OP's question was where is the spark plug. Spamming a forum site is a very very very good way to turn people off to any product. Hate has nothing to do with it......people don't hate a rude interrupting child.....they just want to put a squirrel in his shorts.Stig.....Karl, where'd you put our box of squirrels ?? You used them last.....