This chapter contains general information concerning the steps needed to obtain access to, and use, an system. It attempts (as does the design and coding of itself) to avoid specific references to particular computer devices and to the peculiarities of any one installation. We will assume, for the most part, that you will be running on a Unix workstation although should still work in more classical environments. Even for workstations of the “same” operating system, some installation-specific practicalities remain. For the NRAO installations, these are described in Appendix Z.