how to create a create a search result bock ?

If you just want normal search results, a Views block should do the trick.
If you want to automatically display related nodes, that's the "More like this" feature which is just being worked on here: #1111852: Add a "More like this" feature.

He's not talking about a separate module.
Have a look at the issue that drunken monkey referenced.
In it, work is going on to implement solr's 'more like this' feature for the solr backend of search api.

First, you'll also have to update the search_api_solr module, otherwise servers won't support the MLT feature.
Second, create a new view for the relevant search index (probably "Default node index"), add a block display with a "More like this" contextual filter and the node nid from the path as default argument and set the block to be displayed on node pages.
You'll also have to restart the Solr server and reindex your content, but that should be it.

No, the "More like this" feature doesn't work with database searches. This would be too complex to implement correctly.