Well, I'll have ago...
Eighth notes, quarter notes, and so on are all to indicate how long a note should last. Music is split up into different "bars", which are measures of time. In 4/4 time, probably the most common time "signature" in rock and popular music, every bar has four beats.
Using 4/4 time, this is a list of some of the different notes:
- Whole note - this is a note that lasts for the entire bar.
- Half note - There are two half notes in a bar, normally. Imagine it like one and TWO and three and FOUR.
- Quarter note - Four notes in each bar, or one on every beat. (ONE and TWO and THREE and FOUR)
- Eighth notes - Eight in a bar, or two for every beat.
- Sixteenth notes - Four notes for each beat.
And it goes on for 32nd notes, 64th notes, etc.
This might not be a very good explanation (in fact, I'm sure it isn't), but hopefully it might be of some use to you.