Make a copy of the first example—we'll just need a basic WMS base layer and a vector layer.

Open up the map in Firefox and enable Firebug. We'll use the JavaScript console to add features to the vector layer.

Let's create some features first. To do so, we'll need to make use of the OpenLayers.Geometry classes. Let's start off by creating a OpenLayers.Geometry.Point object, passing in a longitude and latitude (type and execute the following in Firebug):

var point = new OpenLayers.Geometry.Point(-72, 42);

Now that we have a geometry object, we can create a feature object from it. We'll use the OpenLayers.Feature.Vector class to create a feature object using the point object we just created. When instantiating, the constructor can take in three arguments—geometry, attributes(optional), and style (optional). We'll cover the Feature class in detail later in the chapter. Create the feature point, by passing in the geometry...