Launch the Safari Web browser on your MacBook Air and go to the official website of Apple. You will of course need an Internet connection to access the website. Safari will be present in your Apple machine by default.
Once the official website of Apple loads, look for the search bar on the homepage. Click it and type “ichat”. Press enter to start searching for the instant messaging, video, audio and screen-sharing application software.
You will see various versions of iChat in the search results. Choose the version that corresponds to the version of the operating system running on your system and click it. Click on the “Download” button to start downloading the setup to your MacBook.
Once the downloading process is complete, launch the setup to start the installation wizard. Follow the on-screen instructions to complete the installation process.