sales order form

Hii Experts!!

I should create a form which is related to sales order subform with fields like type, no, quantity, qty to ship. This form should attach to the menu items in the sales order. My condition is that when I press the menu item in sales order I should see the form and when I enter values in that form it should automatically update in sales order sub form…please explain the process how to write code and where to write…? I am using 2009 r2 classic client

This means you have to create sales order based on details entered in another form isn’t it ?

After entering the values in that form those values should automatically retrieved in the sales order subform