Create a local directory where you want to store the files you checkout from the repository. My choice was c:\checkout\gallery-contrib
In Windows explorer, find the folder created in step 2, and right click it and select SVN Checkout
Enter the URL for the SVN repository in the corresponding field and verify that the Checkout directory is set to the directory of your choosing.
You can view a list of the available Repository URLs here. After you enter a Repository URL you can browse it by selecting the ... button and click your way around the Repository tree.
When you are satisfied with your selection, Click 'OK'
A new window opens showing the progress of your checkout and once it's done you will be presented with a dialogue like this:
The selected checkout directory should now be filled with the files from the checkout and the green checkmark on the folder icon indicates that it is indeed an SVN checkout
The checkout folder should now contain all the files from the checkout.
If you want to update the folder later on, simply right-click the checkout folder and select SVN Update and the local copy will be updated with the latest code from the SVN repository.