You need 3 pieces of pallets preferably with smooth surface. You may want to use sandpaper to polish the pieces thoroughly especially the seating sections.
After you have done this, it's time to paint the pallets. You may chose your desirable color and start painting. Let the pallets dry thoroughly before you continue.
You may use door hinges and attach the backrest part to the middle pallet. You'll also need to attach hooks and chains from the both sides that will hold the backseat part in the right position.