First, you should create a form using Contact Form 7 plugin, then you can use shortcode to add form into any places you wish.

[contact-form-7 404 "Not Found"]

Pictures

 
1967 Chevelle SS 13 1967 Chevelle SS 20 1967 Chevelle SS 28 1967 Chevelle 27 Plymouth Roadrunner 37 1968 Plymouth Roadrunner 1971 Pontiac Formula 400 1965 Mustang Coupe- OCD Customs 1965 Mustang Coupe- OCD Customs 1965 Mustang Coupe- OCD Customs