Salesforce PHP Development Custom API

General information for the website: Need a PHP script that integrates into Salesforce

Kind of development: Customization of existing website

Description of requirements/features:

I need a php developer that is familiar with the Salesforce.com API. https://developer.salesforce.com/page/PHP_Toolkit

I want to be able to push a message from a web form into a Salesforce contact email activity. i.e. Within salesforce.com you will see email "Activity History" under each contact (See screenshot attached). I want the form message with the relevant allowed fields and attachment to appear in this area when the php script has been run.

I can create the relevant form so I just need the php script that takes the posted information from the form and push it to salesforce.com using their API. I have been informed there is not a pre-created API script for this so a custom script will need to be developed using the @invocable method. See https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_classes_annotation_InvocableMethod.htm

Let me know if you have any questions?