Changing plugs on a motorcycle is good yearly maintenance. It's easy enough to do yourself, follow along with your owner's manual and these steps and pictures.
Step 1
Gather your tools. You'll need the tool kit that came with the bike, and probably the manual to follow along with. You need your new spark plug CR8E (NGK) or U24ESR-N (DENSO). It costs about US$8. 
Step 2
Look at your new plug. By the manual you should have a gap that is 0.70-0.80mm (0.028-0.031 in). You check this with something called a feeler gauge that looks like this picture. 
This tool is just a pocketknife full of different thicknesses of metal. The 'gap measurement' is the number stamped on the feeler blade that will fit between the plug's electrodes without being forced.
Step 3
Prop up your bike and get to work. For guaranteed safety, you could disconnect the battery first. First locate the plug. It's in here: 
This is good, you don't have to remove any parts of the faring (plastic body) to get at it. A closer look is here: 
The plug has a connector wire on it that might be kind of hard to remove by hand. Treat things gently, you can use the small pliers in your toolkit to slowly and deliberately lift the wire straight off the plug.
Step 7
Quick comparison. Old vs New. In this case we probably could have got away with scraping the old plug clean. But the plug is 2 years old already. 
Step 8
Place the new plug in. FIRST screw the new plug in by hand until its firmly seated. Don't force anything, cross threading on the engine block itself would be horrible. Honda is pretty particular about tightening with the spark plug tool: New NGK Plug directions:
A) Tighten a 1/2 turn after plug seats.
B) Loosen the plug.
C) Now tighten plug again: 1/8 of a turn after it seats. 
Step 9
Replace the spark plug wire. This went back on a lot easier than it came off.
Step 10
Done. It's pretty satisfying to do simple things with a bike yourself. This is simple enough that it can become an annual maintenance thing. A motorcycle should be a great way to learn more about mechanics. You don't need to have ramps, jacks, or a lift. Assuming you also have a car, if you fumble bike maintenance then you still have a ride in to work the next morning. Keep your mind and wrenches turning.
Warnings
- Inspect the Plug! The 'gap' between the two electrodes must be a certain width, or you risk damaging the bike. (Or it just might not work at all)
