To insert a divider slide into PowerPoint, try the following steps:

1. Open the PowerPoint presentation.
2. Select the Slide Sorter from the View tab dropdown menu.
3. From the Home tab, select New Slide.
4. Select the blank slide (the ninth slide) from the left pane.
5. Click on the Format tab.
6. Choose the Format Background icon at the bottom of the right pane.
7. Choose the desired background color.
8. Select Apply to All to apply the formatting to the entire presentation.
9. Once the changes are accepted, the divider slide has been inserted into the PowerPoint presentation.