How do I create a key and secret so I can publish to a bucket?

My code that I have inherited has the following:

var publisher = awspublish.create({
        key: 'xxx',
        secret: 'xxx',
        bucket: 'yyy',
        region: 'ap-southeast-1'
    });

But in S3 I am not sure. How do I create the key and secret ? and then make it so I can use these to publish to my bucket?