Please could you help with this:

I have to date labels:

A. Date Label for a register date in an App

B. Date Label for end of the course of the App

The Course is a 45 days training App. I need:

1. Enter the register day manually (ok)

2. Change or add automatically the "date label for end of the course" (+45 days of the register)

3. Sent or create a task for the CRM User

4. Sent an email for the lead or contact register

I´ve tried with task and others but I couldn't...

Thank you