Hello! I will try to help you update the maps on your TomTom...
First, please disconnect your TomTom from your computer.
Then, you'll need to install the TomTom Home software. You can download it from this link...
Once there, please click on the blue "Download" button for your particular operating system...Windows systems is the one on the left...Mac OS is the one on the right.
After you've installed the software, then launch the software (through the desktop shortcut or start menu) and then connect your TomTom. It should automatically detect your device and allow you to update it at that time.
If you have anymore questions or run into any problems, please let me know and I will reply as soon as possible to try to assist you further.