Once the plugin is installed, go to Contact Form on the WordPress Backend and configure all settings. If you want to enable saving form submissions to a database, go to Contact Form > SQL Options and check the box and fill out all information.
Form submissions can be viewed by going to Contact Forms > Form Submissions
To place the contact form, use the shortcode [pcf_contact_form].
The contact form has some default styling, but it can be changed under Plugins > Editor by selecting PCF Contact Form and editing pcf-contact-form/css/pcfcf-style.css.
See the documentation for more detailed instructions.