Commerce Event Registration How to create a commerce site which also has the ability to take registration information during/before/after registration?

I am developing a website which offers a variety of training courses. When adding a particular course to the basket, I would like the to be able to take the details of the people (multiple attendees) who will be attending the course.

How can this be achieved?
There's a module for that: Commerce Registration. You've got a registration field attached to your commerce products and you can work from them to build a solution, for a distribution that uses this for events check out COD, that might fit your needs.