I already built NAS using arduino Uno and i can see it form my computer when im connected to network
is there a way to access it outside the netework?
What do you mean with outside?
You can access the UNO over Serial, the SPI port or even I2C but that might not be what you meant
An Uno NAS? Tell us more about how you built that..
If there was the criminals of the world would have a great time.
It can be done, but is difficult for a reason.
Research port forwarding or use a company that provides the service of publishing your domain on the internet.