Welcome to Justanswer.com, my name is ***** ***** I will do my best to assist you.
Not all Nextar GPS devices have map updates available. Can you locate of find the model number of your Nextar so I can try and guide you.
Also, I need to know what type of computer you are using, a Windows XP, Vista, Windows 7, Windows 8, Windows 10 or a Mac.If its a Mac, please check the OSX version as follows, Click the apple sign at the top left of your screen, then click about this mac. And then where it says version, send that to me as a reply.