I'm now reading the official Scheme specification, the R5RS. Some things make more sense in the spec than they did in Fixnum. Also, macros are defined using define-syntax or let-syntax, but Fixnum used define-macro, which I assume is a macro itself. I have not yet figured out how to use define-syntax; my first experiment failed.
I haven't yet reached the part in R5RS about continuations. We shall see if it helps me any.