How can i go about defining a same table relation mapping (mappingbycode) using Nhibernate

for instance let's say I have a class:

public class Structure{
 public int structureId;
 public string structureName;
 public Structure rootStructure;
}

that references the same class as rootStructure.

 mapper.Class<Structure>(m =>
            {
                m.Lazy(true);
                m.Id(u => u.structureId, map => { map.Generator(Generators.Identity); });
                m.Property(c => c.structureName);
                m.? // Same table mapping 
}
 ;

Thanks