You must catch the bus and ask to Santarém to land in Gauchinho Supermarket. There, cross the road and take the bus to Alter do Chao. After a 35min trip, land a stop after the stop of the cemetery. Follow to the corner, turn right and walk two blocks. Around the corner, turn left and walk one block. The Hostel Pousada do Tapajós will be on the corner ahead.