Adding the Messaging Component to the Lightning Record Pages

1. Use the quick find box to go to Setup > Object Manager.
2. Click Messaging Session:
   
3. Click Lightning Record Pages, then click on the record page that belongs to the app in which you will use the plugin.
4. Click Edit:
   
   
5. Create a new tab with a custom label (for example "Language I/O" or "Translations")
6. From the left pane, drag the Language I/O Messaging component into the newly created tab then click Save.

Your application is ready! You have successfully installed Language I/O Messaging for Salesforce.