I am a beginner and I would like to make an application with :

Front-end : React js
Back-end : Node js

my interface will contain 2 buttons : Download and Send, I would like to download csv files from a sftp server and when we click on download files will be displayed in the interface and the send button allows to send files from my local machine to the sftp server.

How can I combine the react and node part, I was able to connect and upload files in nodejs but I don't know how to combine that with React?