Step 1: Download
You need to download several things to get Canoo started.
a) Download Canoo from http://webtest.canoo.com/webtest/manual/WebTestHome.html
b) Download at least JDK 5
c) Download at least Ant 1.7.0
Step 2: Configure your System-Path
You have to add each of the programs above to your system-path.
E.g. for Canoo its necessary to add the bin/ directory to your system-path, e.g. for Windows "C:\Programme\Canoo\bin";%PATH%
Finished ;)
It's that easy.
For working with Canoo you can either use the built-in test-project or you simply generate your own Project folder with your test-cases in it.