be aware that you can ONLY put a bag in another bag or a box if it is empty.
You can not take a bag full of stuff and place it in another bag or box.
Beyond that it's simple drag and drop - and if you are out of empty slots in your bank try your house vault - even a 5s per week single room starter apartment at the local inn gets two house vault slots. In a pinch you could also stash the bag in one of your broker slots and just not set any sell prices.
"Well, my days of not taking you seriously are certainly coming to a middle."
~ Mal Reynolds