Draw a smooth curve - Quick help

I want to draw a curve, which must be very smooth, but can not find out the right way to do.

If you guys know how to do this, please help me out.

thanks a lot

select the pen tool. make 3 points in a straight line, and pull the one in the middle up while clicking shift.
if you dont know what the pen tool is, how the bezier's work, and how to stroke a path. you may want to get you a photoshop book.