Gilson,
A marko file needs to be rendered to produce output. Typically the output is HTML. A common use case is to render a template out to a file or out to an HTTP response.
First check out how to load a template:
Next, take a look at the Streaming API:
This section shows how to render a template to a "index.html" file.
An HTTP response object is also a stream this code is also common:
require('./my-template.marko').render({a: '123'}, res);
The {a: '123'} argument is just data that becomes available in the template via the "data" variable.
For example, to render the value of the "a" property in your template use:
${data.a}
You can also bundle up compiled templates and use these templates to render data in the browser. My guess is that you're starting with server-side rendering but client-side rendering of a template is also really powerful.
Let me know if I can help with anything else!
Thanks,
Phil