You can download the manual
here. Charging instructions are on page 48.
Depending on the package you purchased, you may have a USB cable. If so, connect the cable to your n?vi and your computer USB port. USB hubs may not be capable of charging the unit.
If you do not have a USB cable, and are not able to charge the n?vi in your car, the fuse in your car vehicle adapter may be bad. You can unscrew the black round end piece from the adapter. This will be on the end that goes into the lighter/power socket. Be careful not to loose the silver cap. The fuse is spring loaded and may pop out. The proper replacement fuse type is indicated on the side of the vehicle adapter.
Garmin also offers an optional AC adapter that can be used without a computer.