In case your MS SQL Server is running on your own computer, you should configure MS SQL Server to allow remote connections. This is disabled by default.
First, download and install SQL Server Management Studio from here: https://docs.microsoft.com/en-us/sql/ssms/download-sql-server-management-studio-ssms?view=sql-server-ver15. You have to click the first link in the article:
Once it is installed, open it and log in to your SQL server.
Right click on your server () and click Properties --> Connections --> Allow Remote Connections.
Next, open SQL Server Configuration Manager and enable TCP/IP if you have not done that already.
Restart your SQL Server.
Make the firewall is configured correctly, so it does not block the port you are using.
And lastly, I am assuming your friend is on the same network as you, otherwise you probably have to configure port fowarding on your router.
More info:
Allowing remote connections: https://docs.microsoft.com/en-us/sql/database-engine/configure-windows/configure-the-remote-access-server-configuration-option?view=sql-server-ver15
Enable TCP/IP: https://www.habaneroconsulting.com/stories/insights/2015/tcpip-is-disabled-by-default-in-microsoft-sql-server-2014