I followed your directions, I cd-ed to the directory that I put the file in, in my new directory it was the only file there. I also installed the rest-client, now instead of

"ruby: No such file or directory -- bittrex_bot.rb (LoadError)"

I get :

"/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in require': cannot load such file -- rest-client (LoadError) from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:inrequire'
from bittrex_bot.rb:1:in `main'" [side note; main was in brackets but steemit wouldn't let me post it]

I feel like there is some progress here, however I am still not getting it, please help.