Using Google Custom Search

HI there – I’d like to use Google Custom Search and the only plugin I can find is really out of date so I followed this guy’s instructions:

https://www.davidrisley.com/2009/01/01/how-to-replace-your-wordpress-search-with-google/

The search results do work, but I can’t get the thing to work with the theme. Does anyone know how to diagnose the template he provided? Or can anyone offer another way to use Google CUstom Search and have the results work in the theme?

Thanks!