Editing User Defined Lists - Beginner

I'm looking to create Macro's which will enable me to edit my UDL's then update their location for drop down box purposes.

As it stands I have long lists of data that are used by cells for drop down validation purposes. It is imperitive for me to be able to add/delete and edit these lists automatically and for this to update into my drop down cells.

Ideally I'm looking for a macro(for adding data) which will either create an input box or go to next free cell in my desired list depending on the macro. The new list then will be updated into my defined name list which will then be able to be accessed from the drop down box.

Any help would be really appreciated.

Thanks