Can I use Publisher to create a simple, quick logo that I can add to my website I am creating w/FrontPage? If so, would I save it as a .jpeg and then insert that .jpeg as a file or picture on my webpage? Please help bc I am not familiar with this and need help. Thanks!

Publisher is NOT a graphics program, it's page layout program.
If you want to create a logo, or any graphics, you need a graphics program, such as Photoshop, PaintshopPro, Fireworks, Illustrator or GIMP (free).