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

 
1969 Camaro 3 1969 Mustang Mach 1 6 Plymouth Roadrunner 36 1968 Plymouth Roadrunner 1960 Buick Convertible 1971 Pontiac Formula 400 1971 Pontiac Formula 400 1960 Buick Convertible 1960 Buick Convertible 1965 Mustang Coupe- OCD Customs