To install the firmware update on your DVD recorder, extract the file from the update Zip file. Write this to CD-R or CD-RW as you would writing files and document to disc. Then pop the written disc into the DVD recorder and give it a moment to recognise it. You should then get a message asking if you wish to perform the update. While the update is in progress, do not unplug the recorder until the update finishes.
If you use Nero or any other software package that supports verficiation, be sure to enable this option when writing the update file to CD-R/RW. I would recommend using a CD-RW free of any scratches, fingerprints, etc. as these can be erased and reused later should the firmware update not work or to avoid throwing out a disc each time you load a new firmware.