If you plan to study in New Zealand, either in secondary school as an international student, or in a tertiary institution you will need to apply for a student visa. There are different requirements for each type of visa.
If you are granted a student visa you may also be eligible to work up to 20 hours per week, depending on the course you are studying.
Once you have finished your studies you may also be eligible for a work visa to extend you stay in New Zealand.
Each case is different, if you think you may qualify for a student visa get in touch to have a confidential discussion.