Open up a brand new blank document in Illustrator.
In the Tools Panel, the 8th tool down is called the Rectangle Tool.
We obviously don't wanna use that, cuz what we're making is ROUND!
So, move your mouse cursor over the Rectangle Tool, and hold down the left mouse button until this little beauty pops up.
Still holding the left mouse button down, move your cursor over the Ellipse Tool and release the mouse.
Now the Tools Panel should look like this.
Check out the Ellipse Tool highlighted there!
Next, we are gonna create the basis for our sphere. What do we start out with? Yup! You guessed it, a circle!
Move your cursor over to the middle of your blank document, hold down the ALT+Shift key on your keyboard, hold down your left mouse button and drag the cursor out about an inch or so, and then let go of the mouse button.
Here's what you get.
What you want to do is fill that circle with with some kind of gradient to give it a 3D feel.
What's a gradient?
A gradient is a color that transitions from light to dark, or, from one color to another smoooothly.
Look to the right side of your screen at the Swatches Panel.
Specifically, the very first swatch in the fourth row down.
The little square that goes from white to black.
If you hold your mouse over it, it will say Linear Gradient 1.
Click on that and now the circle you made will be filled with a gradient
To help your little circle on its way to becoming a sphere, you want to make it look like the sun is shining down on it. Go up to the menu bar, click on object-transform-rotate.
When the rotate menu pops up, type in -45 then click on the OK button.
Now your circle will look like this.
For the last part of this, you want your circle to have a shadow, so go up to the Menu Bar, click on effect-stylize-drop shadow.
When the drop shadow menu pops up, click OK and now you have your finished sphere.