Open Adobe Illustrator CS5 (Start > All Programs > Adobe Illustrator CS5.
Start a new document (File > New) with the following settings:
Select the ellipse tool:
Drag out a circle - Tip: hold down the shift-key while you draw to constrain the shape to a perfect circle.
If you don't have the color red you can change it on the options setting at the top of the document window:
Click and hold down on the Pen tool in the tool box to display the hidden tools beneath. Then drag across to the tear off bar and release the mouse to separate the pen tools palette.
With the convert anchor point tool simply click once on the anchor point at the bottom of the circle.
Your circle should now look like this.
Use the Direct selection tool to select the anchor point at the top of the circle and move it down so that the top of the shape is close to flat.
Use the direct selection tool to select the anchor point at the top of the circle.
Then use the convert anchor point tool and select one of the direction handles attached to the anchor point and drag it up till the curve at that side of the anchor point looks appropriate.
By converting the anchor point we break the connection between the two direction handles so that we can move them independently.
Once the connection has been broken we can then select the anchor point again with the direct selection tool so that both direction handles are visible then use convert anchor point tool to select the direction handle on the other side and draw it up.
Your heart should look similar to the one below: