ActionListener for datatable....

Hi guys,
i'm crazying with these datatables and with my problems with them...
i've read BalusC article and all the posts about datatables...but i
haven't found a clear response to my problem.
I've a datatable

<h:dataTable
    value="#{biosamplesTable.biosamples}"
    var="biosampleItem"
    binding="#{biosamplesTable.biosampleDataTable}" border="3"
bgcolor="pink" >
    <h:column >
        <f:facet name="header">
            <h:outputText value="Organism" />
        </f:facet>
       <h:selectOneMenu value="#{biosampleItem.organism}">
        <f:selectItems value="#{biosample.selectOrganism}"/>

       </h:selectOneMenu>
    </h:column>

    <h:column>
        <f:facet name="header">
            <h:outputText value="Treatment Protocol" />
        </f:facet>
        <h:inputText value="#{biosampleItem.treatmentProtocol}" />
    </h:column>

    <h:column >
        <f:facet name="header">
            <h:outputText value="Extraction Method" />
        </f:facet>
        <h:inputText value="#{biosampleItem.extractionMethod}" />
    </h:column>

    <h:column>
        <f:facet name="header">
            <h:outputText value="Actions" />
        </f:facet>

       <h:commandLink
        value="Invia dati biosample"
actionListener="#{biosamplesTable.editBiosample}" id="editBiosample">

        </h:commandLink>

    </h:column>
    <h:column>
    <h:messages globalOnly="true"/>
    </h:column>
</h:dataTable>

and it works fine,allowing user to send each row of data with
actionlistener.

Now i want to add an actionlistener to datatable that when it's clicked
it add a new column to mydatatable of empty values(i'm using this
datatable for input operations).
I thinks it's an easy question,i ask you to help me with some code..
this is my code...

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import javax.faces.application.FacesMessage;
import javax.faces.component.UIColumn;
import javax.faces.component.UIInput;
import javax.faces.component.UIOutput;
import javax.faces.component.html.HtmlDataTable;
import javax.faces.context.FacesContext;
import javax.faces.el.ValueBinding;
import javax.faces.event.ActionEvent;
import javax.sql.DataSource;

public class BiosamplesTable {
    private List biosamples= new ArrayList();

    private HtmlDataTable biosampleDataTable;

    private Biosample biosampleItem;

    private int nrows;

    private int load=0;
    public HtmlDataTable getBiosampleDataTable() {

        return biosampleDataTable;
    }

    public void setBiosampleDataTable(HtmlDataTable biosampleDataTable) {
        this.biosampleDataTable = biosampleDataTable;
    }

    public Biosample getBiosampleItem() {
        return biosampleItem;
    }

    public void setBiosampleItem(Biosample biosampleItem) {
        this.biosampleItem = biosampleItem;
    }

    public List getBiosamples() throws Exception {

        loadBiosamples();
        // Reload after every request.

        return biosamples;
    }

    public void setBiosamples(List biosamples) {
        this.biosamples = biosamples;
    }

    public void loadBiosamples() throws Exception {

        if (load==0){

        for (int i = 0; i < nrows; i++) {
            Biosample biosample = new Biosample();
            biosamples.add(biosample);
            setBiosamples(biosamples);
            load=1;
        }
        }
        else
        {
            setBiosamples(biosamples);
        }
    }

    public int getNrows() {
        return nrows;
    }

    public void setNrows(int nrows) {
        this.nrows = nrows;
    }

please help me and excuse me for my many posts about this problem,i've
learned much,but i'm not able to solve my problem.......
please help me..