How do I copy a film from a dvd+r to a dvd-r?

Answer 1

rip the film on to your computer then burn it to the dvd-r using roxio or nero

Answer 2

You need a DVD writer that can handle both the "+" and "-"formats.

If you have one do a "disk copy",
let it read the + disk
let it write to the - disk

A DVD writer drive can tell the difference between the + and the - disks. You do not have to tell it which is which.