Depending on how forms on your website work, they must be tracked differently.
How to track forms that redirect you to a different page after submission
To track these forms, you do not need to do any special setup.
Your tracking tool will automatically track when the “success page” is displayed. Just find it in your traffic reports.
You can learn how to use these fields from this documentation article.
How to track search forms and forms that refresh the page after they are submitted
To track such forms you should use the “Track form submissions” settings in your chosen tracking tool settings page.
How to track forms that do NOT refresh the page when they are submitted
To track such forms, you should track when the “Success” message shows up on screen. You can do that with the “Element visibility” settings in WP Full Picture.
How to track other forms
Find in WP FP settings fields for tracking clicks and use them to track clicks in the “Send” button of your form.