You might find Excel a bit easier to use.
It sounds like a fairly straightforward requirement, but I appreciate if you don't know Access it might not be so straightforward.
I'm not sure about online tutorials but there are some good books out there.
As a starting point, I would think about what information you want to store - these would be the 'tables' in the database e.g.:
cadets (stores information about the cadets)
inventory (basically each item of clothing)
inventory_issued (a historical record of inventory, which cadet it was issued to and when, when it was returned etc.)
And that is probably it from what you've said?
You can then go into Access and start creating those tables.
I'd be happy to walk you through all these via email / here.