First, make sure the plugin "Contact Form 7" is installed and activated.
If is not installed, go to WP-Admin > Appearance > Install plugins.
When "Contact Form 7" is activated, go to WP-Admin > Contact.
Here you can create a new form or, if you have imported the demo content, you already have a form to edit.
Once the form is created, it will gives you a shortcode. Copy/paste the shortcode on the page or section of the site you want the forms to appear.