How I can make circle direction move

Hi all, how I can make circle direction move?

Example:

<img src="http://img29.mediafire.com/c234a5f17943576ac0478ab50e92a558d70d7288accc21da4121545f33409d495g.jpg" border="0" />

If Left arrow is down: player move left (around). If right - right...

But if player don�t touch any keys - spaceship don�t move.

Game template: mediafire.com

PS. I has instaled C2 three days ago and don't know simple things :)

I'm making a game with similar movement for my rotary compo game

By using this expression:

X = centerX + sin(a/pi)*radius

Y = centerY + cos(a/pi)*radius

Where a is the period of the movement

You get this:

<img src="http://i.imgur.com/uzv1U.jpg" border="0" />

World.X/Y is the center of the level

Speed (global var) is speed + playerX (which is changed by pressing left/right)

Height (global var) is height + playerY (or can be a fixed value, for constant distance)

Thanks :D ! but I make something wrong and my spaceship does not move. And I don't know why. :(

If not so hard can you see where my problem?

mediafire.com

I'll be very grateful :)