In this tutorial I will show you have to draw a basic smiley face icon. Start out by making a circle with your circular selection tool, holding shift to make sure its a perfect circle. Create a new layer, and fill the circle with a yellow-orange radial gradient. Make sure the light yellow color is towards the top-left, as seen below.

Contract your selection by 4 pixels by choosing Select > Modify > Contract, and entering a value of 4. Use your gradient tool to fill the selection, but this time we are going to change the colors and gradient mode. Change your foreground color to white, and click on your gradient tool. Towards the top left of your screen, change your gradient mode to "foreground to transparent." Fill your selection.

Create a new layer, and make a oval selection as seen below. Change your background color to a light gray, and your gradient type to "linear" and fill your selection.

Contract your selection by 3 pixels. While holding alt, use your circular selection tool to subtract the bottom portion of your gradient. Change your gradient mode back to "foreground to transparent" and fill your selection.

Add a pupil to the eye by filling a small circle with black.

Duplicate your eye layer by choosing Layer > Duplicate layer. Position your new eye to the left as seen below.

Merge your new eye layer by pressing Ctrl+E. Now Ctrl click your eyes layer to make a selection of both eyes. Create a new layer below your eye layer, and expand your selection by choose Select > Modify > Expand and choose a value of 3. Change your foreground color to yellow and your background color to orange, and fill your selection with a linear gradient, making sure the orange is towards the top.

Ctrl click your initial circle layer to give yourself a selection of your entire smiley face. Contract your selection, depending on how wide you want the mouth to be, by choosing Select > Modify > Contract. I used a value of 10. Now use your circular selection tool, while holding alt, to subtract your selection to form a smile, as seen below.

Fill your selection with black.

Your done! Here is how mine turned out: