To be able to use JDBC you need to have the JDBC driver of your database on the class path of your application.

There are multiple ways to connect to a database, but the common ways are to either use the java.sql.DriverManager, or to configure and use a database specific implementation of javax.sql.DataSource.

A simple example to create a connection to a database with the url jdbc:somedb://localhost/foobar and execute an update statement to give all employees a 5% raise:

try (Connection connection = DriverManager.getConnection(
        "jdbc:somedb://localhost/foobar", "anna", "supersecretpassword");
     Statement updateStatement = connection.createStatement()) {
    
    updateStatement.executeUpdate("update employees set salary = salary * 1.05");
}

For further details see creating a database connection