Hi ThaHighLife,
Unfortunately the free upgrade was only available for a period of time.
You can upgrade to Windows 10 from the following website: https://www.microsoft.com/en-au/software-downlo...
You will need to download the media creation tool and run through it. It will ask you a few questions like if you want to retain your data/applications.
Once it upgrades, you will need to input a product key to license the software (otherwise you will see a Windows unlicensed watermark on your screen).
Hope this helps,
Nathan