  In this work we use electrostatic control of quantum Hall ferromagnetic
transitions in CdMnTe quantum wells to study electron transport through
individual domain walls (DWs) induced at a specific location. These DWs are
formed due to hybridization of two counter-propagating edge states with
opposite spin polarization. Conduction through DWs is found to be symmetric
under magnetic field direction reversal, consistent with the helical nature of
these DWs. We observe that long domain walls are in the insulating regime with
localization length 4 - 6~$\mu$m. In shorter DWs the resistance saturates to a
non-zero value at low temperatures. Mesoscopic resistance fluctuations in a
magnetic field are investigated. The theoretical model of transport through
impurity states within the gap induced by spin-orbit interactions agrees well
with the experimental data. Helical DWs have required symmetry for the
formation of synthetic p-wave superconductors. Achieved electrostatic control
of a single helical domain wall is a milestone on the path to their
reconfigurable network and ultimately to a demonstration of braiding of
non-Abelian excitations.
