HSI is a command-line interface for data storage and retrieval from HPSS. While HSI is the most frequently used HPSS client at NERSC, until now there has not been a convenient single document explaining how to best use HSI with the NERSC HPSS systems. This can present difficulties for NERSC users new to HPSS, especially since the NERSC HPSS system configuration and authentication mechanism are unique. In this paper we explain how to obtain and install HSI, create a NERSC authentication token, and transfer data to and from the system. Additionally we describe methods to optimize data transfers and avoid common pitfalls that can degrade data transfers and storage system performance.