How can I solo mine using Bitcoin Core? I want to mine Bitcoin using the Bitcoin Core client.

I have followed the steps on https://www.youtube.com/watch?v=Xd4Opw0Upok, but when I type "setgenerate true" in the console, it replies with "Method not found (code -32601)"

How can I mine Bitcoin with Bitcoin Core?
You cannot.  The mining functionality was removed in version 0.13.0 since it was hopelessly inefficient.  See Since which version the mining functionality removed from wallet?

It is not practical to mine Bitcoin without recent specialized ASIC hardware.  See In the ASIC-age, is it worth starting mining Bitcoin at home?