Since you didn't say which version, the following is for PowerPoint 2003.
Create a bullet slide.
Choose Fomat - Slide Design. Click Color Schemes then Edit Color Schemes. Select your colors. Click Apply.
Choose View - Master - Slide Master. Click Insert - New Slide Master. If you want, Choose Insert - New Title Master. Make your format changes. Customize your bullets. Add footers.
Return to normal view.
In the left pane, on the Slides page, select the slide at the top of the list. Hold down Shift and then select the last Slide. Press Delete to delete all extraneous info.
Choose File - Save As.
Give it a file name.
From the Save As Type drop down list, select Design Template.
Click Save.
You must close PowerPoint and reenter to see your design in the Design Pane.
Or you could have looked the above up in a book.