VMWare has fairly complete instructions that come with Fusion.
Just follow those steps: http://www.vmware.com/pdf/fusion_getting_started_40.pdf
Scroll down to the Contents page, and click on the Getting up and Running section. That will take you through the process to install whatever OS that you want to use with VMWare as a guest OS.
Is that not working for you?
Windows is commercial software, and is unobtainable for free. There is no way to acquire Windows without spending money.
With that being said, you can purchase Windows online (they ship to almost every country, I believe -- unless you're under extenuating circumstances that disallow you to be shipped to) from many different vendors.
A few other options:
1. If you have a physical Windows machine that has an image of the system that would suit you, you could use that.
Install VMware Converter, and convert your physical image to a virtual machine.
Copy the virtual machine after to your Mac.
Launch VMware Fusion, and launch the virtual machine you just converted. Install VMware Tools, restart the VM and you are good to go.
2. Use any other computer that has a DVD drive. A Windows or Linux one works too - use some other VMware software if needed, to create a virtual machine of the type you want (Windows 7), set it the attributes you want (RAM, HD size etc), and proceed in installing the OS from the disc you have available.
After the install, move the image to your Mac, and proceed as above with the VMware Tools for Fusion.
3. If you have a Windows 7 VM in any other VMware product, you could move/migrate that to your Fusion system. Again, you need the up to date VMware Tools with your version of Fusion.
I remember seeing several disc images on Microsoft's site for developer versions of Windows. If you have a developer access to any of those, that could be a solution - just get the disc image file (you'll need a serial that works for Windows though), and point to that in Fusion when you are installing and setting up the Windows 7 VM.
If that's not an option for you, then one of the above. If a VM asks whether you moved it or copied it, you moved it.
Oh, and if you have an external DVD player for Mac or even some Windows thing, try it with your Mac. To my surprise, an external DVD drive that came with a Dell worked directly without any problems on a MacBook Pro.