How do I operate the vacuum bag on the craftsman LT100 riding mower?

Hi,
Is this an LT1000? And do mean the bagger. Always engine at full throttle, will not hurt it as it is below speed that the engine horsepower is rated at.
Peace,
Clarke

There is no actual vac bag but there is a grass catcher attachment. This is a black plastic hopper with 3 baskets and 2 tubes from the mower deck. Is this what you are asking about?