To get started, you can make a website for the developer, tell about yourself, show a portfolio and a list of services that you offer.
Further, the easiest way is freelancing (Fiverr, Upwork, etc.), you can take freelance orders yourself and transfer them to him if he does not like this option.
In addition, you can try to run ads on the site in the same Google, there is really a lot of competition in this niche, but you can always try.
And finally, you can call companies and send commercial offers.
The services of programmers are now required by a large number of companies, many new products are being launched, support for old ones is needed, and it is very difficult to find a good programmer, so if a person is worthy, there should be no problems finding a job for him.