  We will discuss how the decays of charm mesons can be used to study light
mesons spectroscopy, by presenting recent results of Dalitz plot analyses using
data from Fermilab experiment E791. Emphasis will be on scalar mesons, which
are found to have large contribution to the $D$ decays studied. In addition to
the usual extraction of decay fractions and relative phases of the intermediate
amplitudes, the Dalitz plot technique is used to measure masses and widths of
scalar resonances. From the $D_s$ decay, we obtain masses and widths of
$f_0(980)$ and $f_0(1370)$. We find evidence for a light and broad scalar
resonance, the $\sigma$ meson, in $D^+\to\pi^-\pi^+\pi^+$ decay. Preliminary
studies also show evidence for a light and broad resonance, the $\kappa$ meson,
in $D^+\to K^-\pi^+\pi^+$ decay. These results illustrate the potential of
charm decays as a laboratory for the study of light mesons.
