Nope, you won't have to do anything. Just plug in the USB hub then the devices to the hub and you'll be fine.
I have a computer that I have an external hard drive and a printer plugged in to that USB ports. A USB port for the printer quit working so all I have is one USB port to run the printer and the extra hard drive. This may be a stupid question when I add the USB hub I'm going to have to reinstall the printer because it will be a different drive letter for the printer. Am I right? If I am right on that what will be external hard drive do? Will I have to reinstall that somehow for the same reason. I hope you follow what I am trying to say.