function init(){
    var map = new OpenLayers.Map('map');
    var imagery = new OpenLayers.Layer.WMS(
        "Global Imagery",
        "http://maps.opengeo.org/geowebcache/service/wms",
        {
            layers: "bluemarble",
        }
     );
    map.addLayer(imagery);
    localWMS = new OpenLayers.Layer.WMS(
        "Local WMS layers",
        "http://127.0.0.1/cgi-bin/mapserv.exe?MAP=C:/Users/gyu1/Desktop/Newfolder/mapserver.map",
        {
            layers: 'polygon',
            transparent: true
        }, {
            isBaseLayer: false
        }
    );

    map.addLayer(localWMS);
    map.setCenter(
        new OpenLayers.LonLat(1.147, 52.472).transform(
            new OpenLayers.Projection("EPSG:4326"),
            map.getProjectionObject()
        ), 5
    );
    map.addControl( new OpenLayers.Control.LayerSwitcher());
}

MAP
    NAME "polygon"
    WEB
        METADATA
            "wms_title" "MapServer"
            "wms_onlineresource" "http://127.0.0.1/cgi-bin/mapserv.exe?MAP=C:/Users/gyu1/Desktop/Newfolder/mapserver.map"
            "wms_srs" "EPSG:4326 EPSG:3857"
        END
    END
    PROJECTION
        "init=epsg:3857"
    END
    LAYER
        NAME "postgis"
        TYPE raster
        STATUS ON
        DATA "PG:host=localhost port=5432 dbname='fusiongeo' user='postgres' password='**' schema='public' table='london' mode='2'"
        PROCESSING "NODATA=-9999"
        PROCESSING "SCALE=AUTO"
        CLASS
            NAME "boring"
            EXPRESSION ([pixel] < 50)
            COLOR 250 100 0
        END
        CLASS
            NAME "mildly interesting"
            EXPRESSION ([pixel] > 50 AND [pixel] < 100)
            COLOR 100 0 0
        END
        CLASS
            NAME "very interesting"
            EXPRESSION ([pixel] >= 100)
            COLOR 0 50 0
        END
    END
END # end map

map.setCenter(
            new OpenLayers.LonLat(1.147, 52.472).transform(
                new OpenLayers.Projection("EPSG:4326"),
                map.getProjectionObject()
            ), 5
        );

http://jsfiddle.net/aguiguy/ZAZN8/
http://jsfiddle.net/UAxun/155/
http://jsfiddle.net/VictorVelarde/DbCgt/

DATA "geom FROM table USING UNIQUE id USING SRID=4326"

DATA "PG:host=localhost port=5432 dbname='fusiongeo' user='postgres' password='**' schema='public' table='london' mode='2'"

CONNECTION "PG:host=localhost port=5432 dbname='fusiongeo' user='postgres' password='**'"
DATA "geom FROM YOURtable USING UNIQUE id USING SRID=3857"

var map = new OpenLayers.Map('map', {
                projection: new OpenLayers.Projection("EPSG:3857"),
                displayProjection: new OpenLayers.Projection("EPSG:4326"),
                units: "m"
        });
  var imagery = new OpenLayers.Layer.OSM( "Simple OSM Map");
  map.addLayer(imagery);

        localWMS = new OpenLayers.Layer.WMS( "Local WMS layers",
                  "http://127.0.0.1/cgi-bin/mapserv.exe?MAP=C:/Users/gyu1/Desktop/Newfolder/mapserver.map",
                  {layers: 'polygon',transparent: true},
                  {isBaseLayer: false} );
        map.addLayer(localWMS);

        var lonlat = new OpenLayers.LonLat(lon,lat).transform(map.displayProjection, map.projection);
        map.setCenter(lonlat, 5);

        map.addControl( new OpenLayers.Control.LayerSwitcher());
    }