Left click the boat.
All you need to do is right click the boat.
you cant
Aim your cursor in the center of the screen at the boat and right click.
First, hold the boat and right click it over water.
A boat.
You can't make a real moving big boat in mine craft without a mod but you can make a row boat.
When destroyed, a boat results in 3 wood and 2 sticks so no, you unfortunately cannot recover a placed boat.
There arnt boats yet
You have to hit the boat a few times to 'destroy' it, making it drop as a collectible item - same for Minecarts.
Minecraft 1.5 and earlier: Right Click Minecraft 1.6 and newer: Left Shift I am guessing you will be playing a new version, so press shift. If that doesnt work, right click.
If you're talking about vehicles, then you can have a Boat, a Minecart, and a Saddle. The Saddle lets you ride Pigs.