OpenLayers WFS vector layer

I'm trying to add a vector layer with a WFS layer and it's not working. Can anyone point a solution?

OpenLayers code:

var wfs = new OpenLayers.Layer.Vector(
                "Stavros Features",
                {
                    strategies: [new OpenLayers.Strategy.BBOX()]
                    ,projection: new OpenLayers.Projection("EPSG:4326")

                    ,protocol: new OpenLayers.Protocol.WFS({
                        version: "1.1.0"
                        ,srsName: "EPSG:4326"
                        ,url: "http://localhost:8080/geoserver/wfs"
                        ,featureNS :  "http://postgis.org"
                        ,featureType: "polygon"
                        ,geometryName: "the_geom"
                    })
                });

In the GeoServer configuration, I have a workspace 'myWorkspace', a store 'myStore' and a layer 'myLayer' and WFS is enabled. Also in the 'publishing' tab of my layer in the 'WMS Settings Default Style' I have selected 'polygon' as myLayer is multipolygon.

What am I doing wrong?

Am I supposed to specify the workspace name in the 'featureNS' property?

Is there a good tutorial for OpenLayers?
I have read the docs which are very poor and the examples doesn't help me always. I have also read the user manual of GeoServer and I found it very good.