This form for preview purposes only.
Now that your form has been generated, you'll have to save and host it to a web server before it can be used.
The web server will need to support PHP, and if you're using "save to file", that file must be write-accessible.
Further instructions here: Form Generator Manual.
Preview form will be generated here.
Simply fill in the settings at left as detailed by the instructions available here:
Form Generator Manual
Recommended Height: ___ px, Width: ___ px.