If you search Viper R/C on YouTue. There is a video that walks you through how to use the VLink- sorry not on my laptop so I can't post the link.
You do need to make sure that you have downloaded the version for your version if VTX- each unit had a slightly different protocol - but all delivers the same performance in the end.
When you plug your VTX into the VLink if an older software is on the unit it will automatically start to update. If you already have a64 on your unit and want to reset all the parameters. You have to initiate the download yourself.