If you have accounts on both Facebook and Instagram, and are wondering how to link facebook to instagram on computer, you can follow the series of steps mentioned under:
Open a web browser on your computer and visit facebook.com.
Enter the login credentials in the required fields and login to your Facebook account.
Go to Settings and click on ‘Instagram’.
Click on ‘Connect Account’ and then choose to allow all the messages in your Facebook account to be available on Instagram.
Enter your Instagram login credentials in the required fields, and click on “Login”.