From the ANALYZE menu choose Fit Y by X and specify your x and y coluimns. This will take you into the BIVARIATE platform.
From the red traingle select FLEXIBLE> KERNEL SMOOTHER.
That will apply a smoothing curve based on what I believe is the LOWESS method. You can use the slider to adjust the stiffness of the curve.
From the red triangle next to "Local Smoother" select SAVE PREDICTION FORMULA.
Hey presto, in your data table you now have the formula for the LOWESS (LOESS) curve.
-Dave