If you need to get some macro shots but don't have a macro lens, an extension tube might be the way to go.
Macro shots are gorgeous. With crystal clear detail, they capture close-ups of some of the tiniest things in the world, but unless you have a lens that is capable of 1:1 magnification, you're kind of out of luck. You can always go out and buy a dedicated macro lens, but that means you'll need to drop some serious money on a specialty item that you may not use very often. Another solution you could try, though, is an extension tube. In this video, David Bergman of Adorama TV explains what an extension tube is, how it works, and some cheap DIY alternatives that can give you similar results.
The idea behind extension tubes is actually really simple. These hollow tubes essentially put more distance between your lens and your camera body, effectively moving the front element closer to subjects so they can be put in focus. I know, I probably made them sound much scarier than they really are, but seriously, people use toilet paper rolls and DIY cylinders made out of construction paper as makeshift extension tubes, so how complicated can they be?
There are some drawbacks to using extension tubes depending on the kind you buy. Some more expensive models maintain an electrical connection with your lens, so you can use your camera's auto-focus and exposure settings while shooting. Others don't have this connection, which makes controlling aperture tricky if you don't have manual aperture rings.
If you're interested in shooting macro images, I suggest going the DIY route first. Have fun, run a few tests, and if you're into it, you may want to get your hands on an actual electronic extension tube, or even a decent macro lens.