Yes, you must add "priming sugar" to the beer when you bottle or it will not carbonate in the bottle.
The 5oz of sugar was meant to be added at the same time as bottling. Unless I'm misunderstanding you, I think you already put the sugar in there. If so, just measure 5 oz (or half cup) of table sugar and add it to the beer 30 minutes before you bottle.
Don't just pour it in. Put the sugar in a small sauce pan with a cup of water and heat it until it just starts to boil. Then, without cooling, pour it into the beer. Then bottle.