If you getting started in Blender you can probally think of a scene or two where you'd like to have reflective surfaces. As of Blender 2.32 this became very easy using the new builtin Raytracer. The raytracer gives us the tools to create realistic looking reflections, with a few simple steps.
If you haven't already, I reccomend you read the Blender User Interface Tutorial, to get down the basics of the Blender Interface. This will help you GREATLY while your learning your way in the world of Blender.
Other than that this is an extremely simple tutorial, which can be used to create awesome effects (ones much more complex than the simple render you see here).
With that said, on to the tutorial!
Ok, the first thing we need to do is get Blender ready to render the reflection. The first thing you need to do is enable raytracing calculation. This can be done in the display settings button window. To the right of the RENDER button you'll notice a set of green buttons. Click the button labeled 'Ray' to make it become depressed, this will enable Raytracing.
Now, time to create a simple scene to have our reflection in. Delete the default cube in the scene and replace it with a plane. Scale your place to be relatively big, we just need something big enough to get a reflection off of. Then above the plane place a UVSphere with the default number of segments and rings, and if you like you can use Set Smooth in the Edit Buttons Window to make it look smoother in the render. When you're done your scene should look something like mine.
Now we're ready to create the reflection. Select the plane if it isn't already selected, then give it a Material. This can be done in Material Settings.
After you've given the plane a material a whole new range of options open up. Access the Mirror Transp settings, they'll appear in the third panel from the left in the buttons window and will be in a tabbed panel. By default the Shaders tab will be selected, simply clicking the "Mirror Transp" text will change the selection.
Now we need to enable the mirror effect. This can be done by pressing the Ray Mirror button then ajusting the settings. I used the settings shown to the left, they'll be alright for this example, however feel free to experiment. You might come up with something interesting.
Now hit F12 to render your Scene and ta-da! The Sphere is reflected on the plane!
Now you've seen what's possible with Raytracing Reflection, experiment with it! There are thousands of different combinations you can come up with that will change the result... so see what happens.
Here endith the lesson.