error cannot open nds download

Every time i download a game the error message comes up " cannot open ",
Please could some one help me with this I have tried downloading the latest version of winrar but still wont work

What browser are you using?Are you choosing "Open" or "Save" when you try to download? You should always choose "Save".

Many thanks for your reply, I was clicking open instead of save.

When you save just extract it onto your desktop.

Ah,I see your problem.Instead of open,choose save.After the Rom finish download,extract it.Make sure you know where you put it.