Go to your nearest dealer and ask to read the Nav manual. Order one while you're there.
When you see the size of the manual you'll know why I suggested this!
In the mean time.
Assuming you know how to turn on the Nav and select "route". Menu button in front of your right knee.
After selecting the type of route, using the up/down buttons, pushing the center button for your selections, you should then see the screens that allow the actual address input.
Again hi-lighting each (up/down, pushing the middle button) will bring up the "keyboard" where you can type in the info.
Hope that helps some but, since the Honda Nav is anything but, user friendly, it's really hard to explain the multitudes of screens, button pushes necessary to input a simple point to point route!