This is a project you can do with programs you probably already have on your computer -- Powerpoint or Keynote (Mac users).
Here are some step-by-step directions on how to narrate over a Powerpoint presentation (these directions should be adaptable no matter what version of powerpoint you have)
Here are some similar directions if you're using Keynote on a Mac
If you need a microphone to record audio with, you can:
Most of your questions about uploading to MediaSpace can be answered here; there's also two phone numbers you can call (listed in the box in the upper left corner) if you run into trouble. This FAQ page will tell you (among other things):
To get started, click on "My Media" in the menu bar of the MediaSpace website: https://mediaspace.msu.edu and then click on the "Actions" button at the top right. Choose "Publish" from the drop-down menu, and you're on your way!