You will use Google Slides to create presentation documents - a bit like Microsoft PowerPoint.
To create a new Google Slide - Go to Google Drive and click the plus sign at the bottom right hand corner.
A window appears choose Google Slides
A document appears - Give your presentation a meaningful name (this will ensure you can find it easily at a later date).
A presentation for you to start creating. This presentation is saved automatically. The tool bar looks very much like Microsoft PowerPoint and has the same functionality.
This presentation will be saved in your Google Drive.