1 -- This can be accomplished by starting with a part of a load and then adding some bales by hand to help brace up the stack.

2 - You need the stack firm enough to hold the first load up or the stacking will be difficult. Firm bales make a firm stack and with some poles to begin with is a big help.

3. You will need firm bales and a tie layers in the load to hold the stack together, See the tie layer three from the top and also on the top there are two across as a  tie.

4 With  firm  bales it is possible to stack without poles.  Experience is the best teacher.