How do I separate tracks and bring them back in ...

Here's my situation: I just got an iPad 2, and I purchased GarageBand. I'm really loving it, but at the same time, I'm having some difficulties with taking tracks in and out and then recording them. For example, in this one song I'm trying to put together, track #2 doesn't need to come in until track #1 has been completed/played. The same is the case for tracks 3 and 4 -- they come in later. After that, I take away a couple of the tracks and so on. I think (hope) you get the picture. I was thinking that I could hookup my minidisc recorder and just adjust the volume controls for each track and record that way, but this is Apple, so there must be an easier way, right?

Thanks for your help.

eselteee