how to change the material in vr using c++ in unreal engine

how to create an vr walkthrough,access the light on/off function and change the material in selected object… first of all the object glowing these object only be change the materials…please help i didnot get any related tuts…
so many errors facing on glowing effect, light on/off the point…
how to create the widget like material shows the users in c++
the above all only to create c++…
sorry for my english.