i suppose you meant you need 2.3.2, not 2.3.1, right?
anyway, in case you're on windows, there's a nice svn client called 'tortoise svn'.
download it from http://tortoisesvn.tigris.org/
it's an extension to windows explorer, once installed, just right-click in your desired folder, select 'checkout', and type in the address of the silverstripe svn repository. just give it a try!
that's it, missed the svn command in the url...
once you got it running now, just a note if you're new to svn: you don't need to do the checkout every once again for new releases, just right-click and select 'update', and tortoise will show you which files have changed. love this svn stuff