Select the Oval Tool (O), and draw an oval like the one shown at right. We'll call this oval A.
Use the Paint Bucket Tool (K) to fill oval A with a color of your choice, select it (double-click on the fill or press CTRL/CMD+A to select the whole object), and then copy it (CTRL/CMD+C) and paste it in place (CTRL/CMD+SHIFT+V). We'll call this new one oval B. Again, while you hold the SHIFT key down, press the UP arrow about ten times (in 100% view mode this will move oval B up 100 pixels).
Next, take the Line Tool (N) and draw a line from the leftmost edge of oval A to the leftmost edge of oval B. Do the same for the rightmost edge of the two ovals.
Now fill the middle portion with the same color as the fills on ovals A and B. Change the fill of oval A to match the top portion of your cube from the previous section. As before, you can use the Eyedropper Tool (I) to sample this color and the Paint Bucket Tool (K) to fill.
Now delete the top half of the stroke on oval B (shown selected in the image at right) to produce a solid cylinder with borders.
To take it that one step further, you can delete all the lines to leave a perfect cylinder.