When you drag and drop a form, sometimes you may want to edit the fields that come with the block you choose.
To do this, hover over your form object and select the style editor button:
In the right side menu, you can now click the 'Add Input' button to open up the add field dialogue:
Click save and your input will be in the form now:
Set the 'key' as the parameter name you'd like for the field input and your new input will pass through with the form submit.