Hey, sorry for the delay. I have been a bit busy.
You can access the DynamoDB or RDS from either Java, PHP, Python type languages. There is usually a driver library that you can import that contains the protocols necessary to talk to the database over the internet or local network.
For our game, we use PostgreSQL RDS and use the JDBC in Java to talk to it. If you are already familiar with a language, just search for the driver library for it. If you are starting fresh, PHP is the easiest to learn followed by Python, then Java. Each successive language is more powerful though, so it depends on how much capability you need.