Don't be so modest, Elizabeth, you're very close. "Undergraduate" means in college (en la universidad), working on your major. Graduate means you have graduated from college (ie university degree) and may or may not be continuing your education. Postgraduate means that you're pursuing a master's or doctorate (or equivalent). I've never heard "undergraduate" or "postgraduate" applied to high school, however, the term "high school graduate" is used to indicate someone with a high school diploma (and no higher degree).

In general, I think it is like this: * Undergraduate (BS / BA - College) * Graduate (Masters, PhD) * Postgraduate (This can be ambiguous. It could mean, "after graduation" which means the same as "graduate" above. It could also mean post-graduate work, which could mean you already have a PhD and you're doing further research "post-doctorate research") http://en.wikipedia.org/wiki/Postgraduate_education