There's probably millions of paths you could go down. In general I think it would be hard to pick exactly what you might like being so young. But at its core CS research is probably the same as most other fields. You don't really have to know exactly what you want to do when you start, but you should aim at doing actual research. You can get an idea of what research looks like from interacting with others. You'll learn that from professors running research groups, people giving talks about the work they're doing, journal papers, etc.
I think just starting as an undergrad you might see if there are any research groups you can be a part of at your school or talks on CS research that you could attend. That would be a good start. See what people are studying and researching and figure out if you might like to learn more about that area as well. If you find an area you like, try to read some papers in that area, see if there are problems you might want to look into further, then see if a prof might guide you in an independent study or some undergrad research.