If you get a hanger bolt set there should be a couple of fat galv washers and rubber cone washers included. Screw the bolt into fixing in wall, offer up sink, slide cone face towards ceramic then galv washer, then nut, the cone will centre in the larger hole in the sink, and tighten evenly and gently. Sometimes a bit of polyurethane packing behind the sink might be required if the back surface is partic lumpy, but proper preparation, etc..
If you get a hanger bolt set there should be a couple of fat galv washers and rubber cone washers included. Screw the bolt into fixing in wall, offer up sink, slide cone face towards ceramic then galv washer, then nut, the cone will centre in the larger hole in the sink, and tighten evenly and gently. Sometimes a bit of polyurethane packing behind the sink might be required if the back surface is partic lumpy, but proper preparation, etc..