How can I setup the Submission Counter Widget?

From what I can gather, I should be able to set the widget so that I can count down the number of submissions (submissions remaining) - however I don't see where I can set this parameter.

thanks in advance

You can set it up on the widget wizard. Click the SUBMISSION COUNTER widget on your form > click the WAND icon > go to the GENERAL tab > then change the COUNTER TYPE to your preferred setting.