Any good tutorial on creating rails client method?

I am new to ruby on rails so i'll do my best to explain my issue. I am working on an issue where I have to create a rails client method to get the data from services (there's a json file created) and render it to UI. I am looking at the current rails method created in our client repository and i see everything is in lib folder. can you guys point me to some tutorial online or any study material so i can get an idea about creating client method and rendering data to UI?

Thanks