how can i specify certain block for specific content type to get in there? In Drupal 7 every content type gets in the "Main page content" block,
so I want every node with "Product" content type to sits in some other block.
How could I?
It sounds like you're looking for the Views module; it's essentially a query builder with a simple-to-use UI. 

You can make a View that lists all the content of type 'product', displayed in a choice of different formats (HTML list, table, unformatted list of content, etc.). You can create different display modes for the View, including a block which you can assign to a region in the blocks admin page as normal. 

The best part is, though, that you also get the benefit of being able to easily choose the sort order of the list, set filters on certain criteria, add AJAX pagers automatically, and a lot more.

Check out Working with Views to get started; you'll be glad you did!