<script src="http://www.openlayers.org/api/OpenLayers.js">
 </script>
<script>
map = new OpenLayers.Map("mapdiv");
															    map.addLayer(new OpenLayers.Layer.OSM());

															    var lonLat = new OpenLayers.LonLat( 2.37995 ,48.82754 )
															          .transform(
															            new OpenLayers.Projection("EPSG:4326"), // transform from WGS 1984
															            map.getProjectionObject() // to Spherical Mercator Projection
															          );

															    var zoom=16;

															    var markers = new OpenLayers.Layer.Markers( "Markers" );
															    map.addLayer(markers);

															    markers.addMarker(new OpenLayers.Marker(lonLat));

															    map.setCenter (lonLat, zoom);
</script>