What distribution are you using? Most of the "friendly" Linux distributions allow you to browse SMB/CIFS (Windows file sharing protocol) networks via the file manger. If this is the case, it should just be a matter of browsing the network, connecting to the server (the NAS device) and viewing the shares.
If not, you can manually mount CIFS/SMB shares from the command line. The simplest execution of which would look like:
sudo mount -t cifs //Server/Share /mnt/mountpoint