The first step is to create your components. They are three main components to create ( Director, Frontend, MatchFunction ). You can choose any programming language to code them. The only condition is that your programming language support HTTP calls or gRPC, which are the two communication standards supported by Open Match.
Here's a list of gRPC supported languages.
If you need some help to start, we are here for you!
We have a tutorial that could help you.