Download the driver. Once downloaded, extract the contents of the zip folder and run the executable. Follow the prompts to install the application.
You will be prompted to enter your authorization key. You can generate and copy your driver key from the mFax web portal.
Check out this article for more detailed instructions. Paste your key and click "Authenticate" to complete driver setup.
Now that your print to fax driver is setup, simply click Print from any application that allows and choose the Print to Fax driver as your printer. You will be prompted to enter the fax number and cover page details. Faxes sent via driver are also accessible for viewing in the mFax web portal.