Stupid Questions

[AC]

Hi all -
I'm new to the scene and have looked at archives and not found any definitive answers (consistent) for the following and was hoping that somebody can answer them for me.

- Can I take a non-self-booting image and make it bootable?
- What is a "dummy file" and how do I use one in conjunction with an existing image? Why?

Thanks and I'm sorry for the newbie questions!