Filling the Sales Order Header - Source for filling the dropdown boxes

Hi,

I am trying to design the User Interface for Creation of sales order using the WebDynpro's. I want to know, what are all those BAPI's i need to use to fill the following drop down boxes.

1. Order Type

2. Sales Organization

3. Distribution Channel

4. Division

As i am new to ABAP., and i am from Java background, i dont know much about the BAPIs used to get the above data.

Could anyone let me know the source to fill those dropdown boxes. Thanks in advance.

Thanks,

Raghavendra