Need info on creating .cue files for burning mp3 albums in single large mp3's

I basically need some info or a tutorial on creating .cue files in order to burn an mp3 album that has been ripped as one large mp3. I’ve looked at other .cue files and I just had a quick question. What do the INDEX 00 and INDEX 01 lines signify and why are they always found right beside each other and about one second apart?