To draw the circle:
1- (on thew tools panel) Click on the oval tool (short cut= o);
2- (on the stage) press ctrl and click and drag to draw a perfect circle, change the color of the circle to white;
3- TO remove the out lines (press ctrl+a (select all) and holding down the shift, click on the fill to de-select it, ad press del, then select the circle and press ctrl+g (to group the circle);
4- (on thew tools panel) Click on the linel tool (short cut= n);
5- (on the stage) click and drag horizontally to draw a horizontal line longer than the circle width;
6- select the line and press ctrl+g (to group the line);
7- with the line grouped and selected press ctrl+d (duplicate);
8- press ctrl+a (select all) an press ctrl+k (open the align panel), then click on align center and middle;
// now you have a circle, and two lines aligned
9- press esq (de-select all);
10- click on one of the lines, and with the shift pressed, press the down arrow to push the line off the center of the circle (not much);
11- do the same as above to the other line but this time press the up arrow instead the down arrow;
12- select the arrows and group them;
13- select the circle and press ctrl+c (copy), then ctrl+shift+v (paste in place), double click the circle;
14- change the color of circle to black, double click outside the circle;
15- select the black circle and press ctrl+shift+s (scale and rotate) and set the scale value to 80%, and press ok;
// now you should see a black circle on top of a bigger white circle
16- select the two circles and press ctrl+b (break apart);
17- press esq (de-select all), and then select the black circle;
18- press ctrl+shift+s (scale and rotate) and set the scale value to 80%, and press ok;
19- change the color of the black circle to white;
// now you shuld see a little white circle in the middle of bigger white donut
20- Make sure the lines are longer than the circle width;
21- press ctrl+a (select all) and then ctrl+b (break appart);
22- select the pieces of the donut between the lines and detete them;
21- press ctrl+a (select all) and then ctrl+b (break appart);
22- with all selected, hold the shift and click in all that is not a line (this way you will de-select the fills maintaining the selection on the lines) and press del.
pronto! you should now see a circle similar to the enter button on that link.
=)