Okay, Sorry it has taken me so long to get back to you guys about this.
Larry's first link told me xxactly what I needed. Thank you, Larry! Although, I don't have any idea what another cable would have done, so I didn't worry about the second link.
I went to a local computer store, and asked the guy for a BNC to RCA connector that Larry recommended, and he whipped this little metal thing out of a drawer, dropped it in my hand, and said "have a nice day!" And that was that.
So I got home, hooked everything up, and finally got to test my cameras. And they're all working like a charm.
So, thank you, thank you Larry! I couldn't have done it without you!
Oh, and tomcctv: There was no need to mention power supply, since the monitor-tester thing had this splitter thing on it to hook up to the existing security camera power supply and the camera at the same time. I just didn't mention it or post a photo of it because it wasn't relevant to the connector I needed. If it has no relevance, and I didn't need to worry about it, there was no point in mentioning it, since it wouldn't have any effect other than clouding up the issue. It's an irrelevance that had no bearing on what kind of connector I would need to hook up the camera to the test monitor. Why waste your time (or anyone else's) worrying about irrelevance?
Again, thank you for answering my dilemma!!