So that you don't do anything wrong when enabling the solo mining functionality and risk misconfiguration, I would highly recommend you to use ready-made cgminer versions that already contain this patch. There are several Github repositories. My own favorite is
github.com/phaenomenon/cgminer, which is quite up-to-date (version 4.12.1) and includes many other useful things besides the actual Golden Guy patch. For example, it automatically checks the given payout address for correctness, only then the mining process starts at all. If you accidentally entered a Bech32 for solo mining, cgminer warns you at startup and aborts with an error message so you can correct it. Also, you can mine not only in mainnet but also in testnet. In testnet you need to provide a legacy address that starts with "m" or "n" and this is also handled by the input validation. The README contains useful information under "SOLO mining" and there are also very cool start scripts included, so you can get started right away.
I also highly recommend reading those two How-To's from
nullama which explains how to mine on testnet using a GekkoScience Compac-F USB miner or even with a GPU/CPU:
[Guide] Solo mine testnet bitcoins with cgminer, Bitcoin Core, and a Compac F[Guide] Solo mine testnet bitcoins with bfgminer, Bitcoin Core, and a CPU/GPU