1. First step would be creating the actual survey - just go to Administration and there choose "Surveys" tab. A survey has to have at least one page and one question, but the number is up to you.
2. Now you can choose which types of questions you need. "Scale" is a great one - just define the grades and make them understandable for users. Don't forget to make the answer mandatory!
3. To automatize sending the survey to all the participants, just add an action and choose the training as an object of it.
4. From now on every user that is present at chosen training, will get the survey - no more configuration for you!