How to add an extra field in new event popup

Actually i am trying to add an extra text field for quantity, like i am trying to add Milk in Description and i need to mention quantity in a field, which should be Stored into the Database. SO kindly Help me out of this problem.

It seems like you need such component as dhtmlxTreeGrid to add extra data in the node

But it will be best, if you clarify your question.
May be attach some screenshots, schemes or samples?