The source in SVN is hosted on the vtp Google Code site. It will be very cutting-edge. You might even catch it at a point where it will not build. If you want something stable, you are encouraged to grab a source archive instead.
If you don't already know how to use SVN, see "GUI", below.
To check out a working copy anonymously over HTTP:
svn checkout http://vtp.googlecode.com/svn/trunk/ vtp
There are many GUI Subversion clients. On Windows, a popular one is Tortoise SVN.
The First Time
- Install Tortoise SVN.
- Open a Windows Explorer, and find the folder where you want to put the source.
- Right-click that folder and select "SVN Checkout..."
The URL of the repository ishttp://vtp.googlecode.com/svn/trunk/Press OK.
After the First Time
- Open a Windows Explorer, and find the "vtp" folder which contains the source.
- Right-click that folder and select "SVN Update".
You can also browse the VTP SVN repository in a web browser at the same URL, http://vtp.googlecode.com/svn/trunk/