First you should take a look at some of the magento 2 resources available (https://magento.stackexchange.com/questions/52753/can-anyone-suggest-more-technical-resources-for-magento-2/52754) or http://devdocs.magento.com/

In terms of adding a block, I'm assuming through the CMS you can use the following:

    {{block class="Xanka\\Slider\\Block\\Slideshow" block_id="block_identifier" template="slideshow.phtml"}}