When using psychological tests and instruments it is crucial that these are obtained and administered appropriately. Many tests require permission for use and distribution, or specific training to administer them correctly. You should discuss this with your supervisor before accessing test material. If you need to request permission to use a particular tool, you can view a sample permission letter here that you can customise to contact authors and request permission to reprint and use their copyright material in your research.
For more information about choosing the most appropriate test and guidelines on how to seek permission from authors to reprint and use their copyright material, you can visit the American Psychological Association's Testing and Assessment web page and the Australian Psychological Society's Position Statement on psychological tests and testing.