As the name suggests, this hotel is in the Grand Place, the nerve centre of Brussels, where you can visit the famous City Hall. It's not difficult to find! It belongs to the famous hostel 2G04, which is cheaper and slightly less central. To check in, you must go to the hostel. If you fly to Charleroi (Ryanair), catch the bus to the centre of Brussels; buy tickets in the airport before boarding (13 euros). The bus will take you 40 minutes to the train station Midi-Zuid. Your best option there to get to the hostel is a taxi or a tram. A cab will be about 9 euros.
Once you've checked in, it's a 10 minute walk to the hotel.