Open a Command Prompt. In Windows 10 you can do this by clicking the Start button and typing "cmd". The Command Prompt Desktop app will appear as Best match. You can either click it or just press Enter to start the Command Prompt.
In the Command Prompt type
ipconfig /all > C:\ipconfig.txt
If you get the error message "Access is denied" it means you do not have sufficient privileges to write in the specified directory. Choose a directory where you have write access.