API connection from web application to Infusionsoft

I am using Laravel 5.4 for our web application.I am trying to create a new contact in our infusionsoft account through a php/html form of our web application with the help of infusionsoft API. I have installed infusionsoft/php-sdk using composer from https://github.com/infusionsoft/infusionsoft-php and configured app.php, .env variebles as mentioned (with client ID & client secret).

Now I want to know what should be the redirect url and exact code to establish an authenticated connection with Infusionsoft to create a new contact after POST data of web form.

Totally struck here. Please help.

Thanks
Nilanjana

The redirect URL will need to be a resource located on a public-facing web service that can collect and store the refresh/access tokens POSTed by the API upon authentication.