Collective and individual spin-flip and spin-conserving excitations of a two-dimensional spin-polarized electron-gas in a semimagnetic Cd1–xMnxTe quantum well are observed by resonant Raman scattering. Application of a magnetic field splits the spin subbands and a static spin polarization is induced. Wavevector and field experimental dispersions are very well reproduced by calculations one when both exchange and correlation corrections are taken into account. A maximum polarization rate of 40% is deduced from measurements.