If you made a presentation in Impress you will be able to upload the presentation file by saving it in Power Point file format:
- Choose File > Save As from the menu bar.
- Select the location where you want the PowerPoint file saved and type a name for the file.
- Under File type, choose Microsoft PowerPoint 97/2000/XP (.ppt).
- Click Save. The message shown below will appear. Click Yes to confirm that you want to save the file in Microsoft PowerPoint format. You can select the checkbox to not show the message again.