How do you punch in and still hear the track?

[Ihatecomputers]

First off, I know NOTHING about computer language, trying to learn but it looks like you need to know technical words to learn technical words. Double edge...Sorry about the lay terms here.

I'm using Pro tools 8 LE with a Digidesign M box on Windows 7.

I am trying to punch in at the end of a single guitar track, to record the other half of the song. I have checked the "quick punch" button and it does not seem to do anything. I tried using "pre-roll", but there are two problems:
1. I can't hear the track I'm trying to record on if it is record enabled. I need to hear it to know when and what to play because it is the main track.
2. If I don't highlight a section, it records over everything. But I want to record for like an additional minute & a half, and I can't highlight beyond where I've recorded up to.

I got this to work once and I don't know how to repeat it because I did nothing different that I'm aware of. I clicked the spot I wanted to start recording, pressed record, then play, and it played from the beginning and recorded starting at the spot where my cursor was just like I wanted.

Please help! And remember I don't know big words!!!!!!!

[anothercolour]

You need to select Auto Input Monitoring.