- Download and install Tortoise SVN - http://tortoisesvn.net/downloads.html
- Install Visual SVN
- Register a new Assembla Account
- Setup Assembla Repository (Note that the free account only gives you 500MB of space)
After you have set up your repository, make a note of your URL of your repo (e.g. https://subversion.assembla.com/svn/RooiWillie/)
Next you need to determine a space on your hard drive where you will place your source (e.g. C:\Subversion\RooiWillie). Create the directory (if you have not yet) and right click. Highlight TortoiseSVN and click Repo-Browser.
Enter the URL of your repo.
You will be prompted for your credentials, just use your Assembla credentials.
And that is it, you can now add files (your VS2012 solution/s) to your repository and check out a working copy.
After you have installed VisualSVN, you will notice a VisualSVN menu in Visual Studio. It piggybacks onto Tortoise, so the dialogs will be similar. You should be able to get your way around.
A good resource will be the tortoise docs:
http://sourceforge.net/projects/tortoisesvn/files/latest/download
*edit - Link Updated