How To Use Audacity To Edit Audio Files

I need to resume with the training after the New Year celebration. As mentioned on my previous post, I will make a presentation on how to create a video. However, I need to prepare first the background music. And so  I've considered using Audacity, a free audio editor and recorder. Though quite familiar with the tool, I have searched and downloaded again  the program for this tutorial.

The slide presentation is finished within the day and it is presented below: