Search builder participants - relative start dates and event types
You don't say what version of CiviCRM you're using, but I can do this using the Advanced Search function. Using this search I can filter by event types and use relative dates for the event start date. It's under the event panel when you're adding in your filters. This will give you a list of unique contacts that meet the criteria.

If you want to see all registrations (including each registration for people on more than one course) you can use the Find Participants search in the events menu. 

Or you can also use the "display results as" feature in the advanced search if you want to build up your search with other non-event data. So you can filter on all criteria in the advanced search and then "display results as" participants to see the unique registrations.