On the PC, you can click on the button shown below if you have completed the registration of your Binance account, and scroll down to find the "API Management" section. In the mobile app, you can click the "More" option in "Home", pull the top menu to the far right to find "Others", and then click "API Management".
Find the Secret Key and copy it.
3. Don't have an account or don't have an API Key? Click How to sign up for a Binance account?