How to display articles in joomla cms? (in own html template)
<jdoc:include type="modules" name="articles" />
but nothing is displayed.
You can't directly show an article in the template. The template defines positions for modules and where the component output goes. How the module positions are filled and what will be shown withing the component container is up to Joomla and how you set the modules, menu items and everything.
Usually articles are shown by the component
com_content, that means an article is shown within the component container (the main part of your site).
However you could use an extension which allows to put an article into a module position. Then you enable this module and assign it to a module position.