how do i download ebooks to satnav,epub file unsupported,ebook readers unsupported wince 6.any help.need ebook reader for wince6 thanks

As you might be able to guess by the banner of our forum : We are a GPS forum, not a Ebook forum!
And if you don't know how to download from the internet noone can help you ;)

You seriously want to read an e-book on a sat-nav?
Well, first of all, I have no idea what device you are talking about, but know that most GPS devices have a somewhat severely reduced version of WinCE...usually just enough to run the GPS software...missing the components from the 'full' WinCE that can run numerous things meant for the extinct PDA.
So that typically means you would have to hunt down those missing components and place them in the same folder as the program (adding them to the Windows folder...if you even can...can be useless because when the device reboots on a GPS, the entire Windows folder can be replaced by the image that the manufacturer decided to use...anything you added would be gone).
But, if you want to go through this trouble, try some of the suggestions here:
E-Book-Reader-and-Win-Ce-6
Then you may need a program called Dependency Walker to see what that program requires that may be missing, then hunt down those missing components.

i know how to download idiot,just wanted to know which format that wince 6 uses.

One more offence like that and you can say good bye to your account.
The intelligence lack is on your side as it is not a matter of the operating system but of the program you use to read the books.