How to check out code:

Windows

Download http://tortoisesvn.net/downloads.htmlTortoiseSVN
First make sure you have an empty folder somewhere, Right Click it, choose SVN Checkout
Go to the Source tab, go to the Checkout subtab, and copy the url only in the command line tab.
Now paste the URL into the URL input box. Press enter and it will prompt you for your Creds.
enter your username as shown on the Source tab, and enter the google code generated password.
Work on your code, and don't forget to commit by right-clicking the folder and pressing commit. Updating works the same way

Make sure you have the Subversion package. Use Sudo apt-get (if you have a fedora or other red hat-based OS, i can't help you, do some googling.) This should work with ubuntu, debian, knoppix, and most other debian-based linux OS.
Once you've installed Subversion, go into your directory where you want to add the repository checkout through terminal (cd is your friend)
Copy and Paste the Commandline line that is shown. This should give you a checkout.
I'm not entirely sure about committing, instead of svn checkout i think you do svn Commit and the local directory, not the URL of the actual repository
You can also try and commit straight from Netbeans. There should be a versioning option somewhere with subversion under it. Then just hit commit, enter your user info, and you're good to go.