Point 1: The head and the torso must have the same face count.
I mean the two circles (bottom of head, top of neck) must have the same vertex count

Point 2: The top polygon of the torso must be deleted.

Point 3: The bottom polygon of the head must be deleted.
If the two objects are closed meshs, you can't merge them properly. /If you are using bool operations (I don't know Wings3D so much), you can merge the two objects. But this creates often ugly anomalies.

Point 4: If you have done all the other things mentioned before, you can target weld every vertex of the head with the torso. Move the head as near as you can to the neck. Then choose the vertexes lying most near to eachother and weld them.

Perhaps someone else can explain the Wings3D specials. This was an explenation for basic polygon modelling.