I’d like to use this math library. How can I use it?

I copied the code and created the file /Users/a/forth/exponent.fth but when I tried to include this I get “no such file” error:

include /Users/a/forth/exponent.fth 
/Users/a/forth/exponent.fth:3: No such file or directory
require >>>/Users/a/forth/modulo.fth<<<
Backtrace:
$100C54EF8 throw 
$100C55000 required 

I changed the address of the required file to my local file as well:

require /Users/a/forth/modulo.fth

What do I need to do to use this library? Thanks.