Ok, this is the way I started to collaborate, hooking up Notepad++ to FTP, backing up crap every 10 minutes in renamed folders really sucked, if you do this, for the sake of your project at least use version control at the server.
An online IDE
Cloud9 is very nice and has concurrent editing, however, it will cost you to have more than 1 private workspace to work with your team, but it is worth it.
If you don't find Git approachable enough by your coworkers, try Mercurial with TortoiseHG, which is a GUI client for Mercurial. It will take them two minutes to setup and less to start using it.
Have them use the GUI, they just have to learn to use 4 buttons (pull, update, commit, push) and learn 2 or 3 concepts in order to save and share their work.
Have them register in bitbucket. Create a repository for your project, and have them fork it so they can work in their own mirror of the repository and that way they don't have to deal with merging. You do the integration and just ask them to issue pull requests from their Bitbucket fork once they've pushed. Have them pull only from your repository (the one they forked from).
Learn Mercurial yourself so that you can solve all related problems, this is a good start: http://hginit.com/
You can use Mercurial from Cloud9, how cool is that?.
If you are the one looking to use the correct tools you are already in a leadership position. Don't assume they're not educated and talk with them about how things are done in the real world.
Be enthusiastic about it an not patronizing.
It really doesn't get any easier than this if you want to do things right. If they expressly don't want to use version control then you might have another kind of more serious problem.