The Microsoft Office Button is always located on the upper-left corner of the PowerPoint window screen.
See the image:
When you click on the button, it displays a menu with multiple options to perform several different tasks.
See the image:
New: To create a new presentation from scratch
Open: To open an existing presentation from your pc
Save: To save the new changes made in an open presentation
Save As: To save the presentation with any specific name or/and to a preferred location in the computer
Print: To print a hard copy of the already open presentation
Prepare: To prepare your presentation for distribution to others
Send: To send the copy of your presentation to other people
Publish: To distribute the presentation to other people
Close: To close an already open presentation