Hello,

At first, please read how to create and add your custom web-part: http://www.kentico.com/docs/devguide/index.html?developing_web_parts.htm

At second, please note that bizform' s data (inserted by editor) are stored in our batabase. Every bizform has its own table, its name you can find in CMSDesk -> Tools -> BizForms -> edit bizform -> General -> Table name. This table contains all fields that you specified.

So, to achieve requested functionality, you can create custom webpart, use two dropdown lists from Toolbox (in your Site Manager) and bind them to appropriate tables in DB (DropDownList tasks -> Configure data source...). Do not forget to set "autopostback = "true";"

Now, if you want to determine displaing data in DropDownList2 in dependace on selected value in DropDownList1, you can use appropriate WHERE condition in SelectedIndexChanged event of DDL1, like this:

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
// custom code with your WHERE Condition
}

You can use similar procedure to fill dataset control. To show the result on your page (using custom web-part), you will need to use GridView control and fill it using dataset control (content of dataset control itself you can see only in debug mode).

You can also note how to add custom actions to a BizForm form: http://www.kentico.com/docs/devguide/adding_custom_actions_to_a_biz.htm

Best Regards,
Radek Macalík