Make Sure you have downloaded the latest version.
Go into google maps, select the directions icon, then after it says start end point, select an end point and after it calculates there is an option to use google navigation
Lost in London? Late in Leicester? Misplaced in Manchester? There'll be no more tears if you're an Android user with no sense of direction, because Google's free sat-nav software, Google Maps Navigation, is now available in the UK.
After a stealthy overnight update to phones running version 1.6 or later of Google's Android operating system, Google Maps Navigation appeared this morning on phones such as the Google Nexus One, Motorola Milestone and Acer Liquid . Unfortunately, HTC Hero users are left out in the cold until the networks can squeeze out an update to its Android 1.5 OS.
I have no idea about other phones not mentioned.