Move the camera to the direction it points

This may be a very basic question, but I do not know how to do this.
I am trying to make a fps type camera and I am using following code to move and setting orientation of the camera

glMatrixMode( GL_MODELVIEW );

glRotatef(rollValue, 0, 0, 1);	// roll
glRotatef(yawValue, 0, 1, 0);	// yaw
glRotatef(pitchValue, 1, 0, 0); // pitch
glTranslatef(x, y, .z); // to move

// then draw shapes

The problem is I can move the camera but not to the direction it points to.
Could you please tell me how to do that?

there are basically two ways, the first one is to use basic trigonometry like this

#define PI_OVER_180 0.017453292519943295769236907684886


or you could get the modelview matrix and then multiply it with the vector you wish to move in (with the fourth value being 0) and get the result directly.