Answer for Using a third party contact form

Hey Kevin..
  Thanks for answering..! The reason I want to replace the contact form that is already within the theme is because I’m having a hard time adding fields and making them work..! Just to get a clear picture of what you’re saying..: I can use another plugin, IF, it supports shortcodes with PHP…? Not certain what this means…I’m planning on using Ninja forms for example..would it work..?
Thank you…