Well you will not have a 'DVD9 writer' as these are commercial peices of equipment that can burn 2 layers of information onto 1 side of a compatible blank DVD R/RW.
It sounds like you more likely have a normal DVD-R/RW or DVD+R/RW burner (DVD 5). Which can burn onto 1 layered 1 sided blank disc's.
There is still cause for confusion with DVD 5 blank disc's because despite being labled as being able to store 4.7GB (4812.8MB) of data, they can infact only store 4.367GB (4472MB) of data.
Anyway to get back to your question. If you have a file, or files that are greater than 4.367GB (4472MB) and you want to burn it onto a DVD 5 blank disc you need to use a piece of software like dvd2one. Which is available at: -
This software is available for a free 14 day trail but does have limitations. It's very popular and even has it's own forum if you get stuck.