Accessing Scheme

Running Scheme: On Solaris machines in WWH: type "rs" to invoke the interpreter.
Initially the prompt says: top . Whenever there is an error, the system creates a new level of evaluation (to allow you to debug the current state) and the prompt indicates the number of stacked levels of evaluation. You can ignore those numbers for now.
To get out of the system: type Control-D. Control-D removes one level of evaluation, so if you have a number of errors accumulated, enter Control-D until the prompt is back at top. The next Control-D exits the system.
Loading definitions : normally you edit your function definitions into a file, and load that file into the interpreter. The command is
(load "myfile.sch")
The extension is arbitrary, the argument must be a string in quotes.

Basic references : Scheme Reference Manual
You should read sections 1-6, skipping assignments, iteration, delayed expressions, and all mutation operations (those whose name ends in "!").
There are number of free implementations for all sorts of targets.