This talk reports on ongoing work with Peng Wang (Tongji University). We will consider Willmore surfaces in $\mathbb{S}^n$ via the loop group method. For this we introduce a "Gauss map" which has the property that an immersion is Willmore if and only if the Gauss map is conformally harmonic. Using a frame lift we will introduce a spectral parameter. Specializing to Willmore surfaces from $\mathbb{S}^2$ to $\mathbb{S}^n$ we show that the Gauss map has finite uniton number. This allows to apply work of Burstall and Guest. As a result we obtain normalized potentials which are contained in some nilpotent Lie algebra. We will give a fairly detailled description of these normalized potentials and we will also discuss, how to construct all Willmore spheres in $\mathbb{S}^n$