How to include the JavaScript source in RoR

Hi guys,

I am a newbie in developing in Ruby on Rails.
I don’t understand how to include the a javascript file.
so like i.e. in general HTML I use this

it seems like I couldn’t do this directly, so I need to put the
javascript file in the script folder.
so how do direct to the file?
also, how about a href and img src?

Thanks in Advance,