How to import other libraries in mit scheme?

This is a newbie question about how to load dependencies in mit scheme

for example, I wish to use the streams library defined here. http://srfi.schemers.org/srfi-41/srfi-41.html

(library (streams primitive)
  (export stream-null stream-cons stream? stream-null? stream-pair?
          stream-car stream-cdr stream-lambda)

 .....
 .....)

what do I do? is it already there because it is a srfi? do I save it as a file? how do I call these functions?

SRFI 41's reference implementation has two variants, one for R5RS and one for R6RS. MIT Scheme is boycotting R6RS, so you should use the R5RS version.

I haven't used MIT Scheme, so I can't say further beyond that. From what I see on their home page, MIT Scheme also appears not to have a module system, so you probably need to just save that file to your project directory and load it in, the old-fashioned way.