How can I use thre Migrate module? I installed the Migrate module, but I can't use it, nor can I find any useful documentation that explains how to use it. The page on /admin/content/migrate is empty. 

How can I use this module?
The Migrate module only provides a flexible framework for data migration into Drupal. The logic and data mappings to perform an actual migration are pretty complex. Migrate does not provides an UI to build or configure your migration. IMHO, this is good because a complete UI to build such script would be at least as complex as writing it directly in PHP.

Its documentation is pretty complete and provides all the information needed to start using it. I recently started to use it and, coming from an OOP background, find it intuitive and easy to learn.