Edit Form Widgets

Hello,

I know I'm a little mess explaining myself, but I will try. I'm telling what I did for asp.NET:

I did a form that searched in a database the data that I wanted to show in my dropdowncontrol, also write in that database when I click submit. To to this I used a connection made in asp.NET and some codebehind to configure, you know how it is done usually.

So, I want now to do the same in sitefinity, I would like to use the Sitefinity.mdf to write the data, if it would be possible, I would like to use the default widgets of the form and configure its parameter to use that database and write the sql statements. As I think, maybe this is not posible, so maybe I have to program my own widget, If I do this, I don't know what to add to the widget to use sitefinity configuration and where to ubicate this file. I nether know how to upload to sitefinity, if it is done as control widgets of pages in advance -> settings -> toolboxes but in other folder for forms or not.

I hope you undertand me. See ya.