Its not as easy as just adding a field to the database, which is simple, the query would be something like:
Code:
alter table dl2_files add column version int not null default 1
But once that's done all the code needs to be changed to add a version field to the page so that one can be entered and then you need to modify the code so that the version is written to the database. After that you need to modify the pages to read the version information and display it to the screen.
It might sound simple but there's a fair bit of work involved.