situation, multiply cost of item with the amount of items on hand for a total on hand cost. which colums to enter criteria in, do I need to set a parameter?

I assume you are talking about doing this in a query. If that is true then in the last empty column in your query put this in the top field:

Total On Hand Cost: [Cost]*[ItemsOnHand]

Change Cost and ItemsOnHand for the actual names of your fields.