how can i collect images from database into folder and show its first images as thumbnail

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C#

ASP.NET

image

I have 3 modules and in those 3 module I have 6 ppt in my database mean each module contain 2 ppt and in those 6 ppts i have 18 pic each ppt have 3 pic. path of the images are save in database.
Module PPT
1 a,b,c a1.jpeg,2.jpeg,3.jpeg
2 d,e,f
3 g,h,i

same with b-i three images in each ppt and 3 ppt in three modulea

what i want on my page is to when user select module from the dropdown list i can see ppt related to that module and when i click on first ppt i can view 3 images inside it as a slide show. how can i do that this is my code but in this i get all the images related to that module i want to show ppt folder first after selecting module and then when user click on that folder user can view slideshow.. just like slideshare.net


How can i do that

this is my code:

<table><tr>
    <td class="style4">
        <asp:Label ID="lblModule" runat="server" Text="Module"></asp:Label>
    </td>
    <td class="style3"><asp:DropDownList ID="ddlModule" runat="server" 
            AutoPostBack="True" DataSourceID="SqlDataSource1" DataTextField="Module_Name" 
            DataValueField="ModuleId">
        </asp:DropDownList>
        <asp:SqlDataSource ID="SqlDataSource1" runat="server" 
            ConnectionString="<%$ ConnectionStrings:WebGallery %>" 
            SelectCommand="SELECT [Module_Name], [ModuleId] FROM [Module_Master]">
        </asp:SqlDataSource>
    </td>
        <td class="style3">
            <asp:Button ID="btnSubmit" runat="server" Text="Submit" 
                onclick="btnSubmit_Click" />
        </td>
        <td class="style5">
            <asp:Label ID="lblMsg" runat="server">
           </asp:Label>
        </td>
    </tr>
</table>

<asp:DataList ID="dlImages" runat="server" RepeatColumns="5" CellPadding="5">
<ItemTemplate>
<a id="imageLink" href='<%# Eval("Imageurl") %>' rel="lightbox[round]"  runat="server" >
<asp:Image ID="Image1" ImageUrl='<%# (string) FormatImagePath( (string) Eval("Imageurl"))%>' runat="server" Width="112" Height="84" />
</a> 
 
</a> 
</ItemTemplate>
<ItemStyle BorderColor="Brown" BorderStyle="dotted" BorderWidth="3px" HorizontalAlign="Center"
VerticalAlign="Bottom" />
</asp:DataList>

.aspx.cs page

protected void Page_Load(object sender, EventArgs e)
    {
        bindgrid();
        //Load();
    }
    protected string FormatImagePath(string Imageurl)
    {
        if (Imageurl != null && Imageurl.Length > 0)
            return ("~/" + Imageurl);
        else return null;
    }
    // In this images are save under module and ppt into a folder which specify by us
    protected void bindgrid()
    {
        con.Open();
        //Query to get ImagesName and Description from database
        SqlCommand command = new SqlCommand("SELECT ModuleId,pptId,Imageurl from Image_Master where ModuleId='"+ddlModule.SelectedValue+"'", con);
        DataSet ds = new DataSet();
        SqlDataAdapter da = new SqlDataAdapter(command);
        da.Fill(ds);
        dlImages.DataSource = ds;
        dlImages.DataBind();
        con.Close();   
        con.Close();
    }
    protected void btnSubmit_Click(object sender, EventArgs e)
    {
        bindgrid();
    }

thanks in advance