You can configure various attributes of an enterprise server instance, for example how much memory is available to it, how many service execution processes it starts up with, what information is traced. Most of these options are fairly straightforward; in any case detailed advice on these options is available in the help for the Add Server and Edit Server pages.
An enterprise server instance and the objects it contains (services, listeners, etc) each have a specific Configuration Information field, accessible on the Add and Edit pages for each type of object. Entries in the Configuration Information field use the .ini file format, with section names in square brackets followed by name/value pairs:
[ASection] name1=value1 name2=value2
Most settings are case-insensitive except the names of virtual paths for the Web listener, which are case-sensitive.