Let the leaves die down and then dig them out and let them dry off thoroughly, then store somewhere like a dry shed, hanging in nets (mice love them).
You can re-plant into pots or the garden but, if the tulips that you grew were fancy ones, the chances are that you won't get many flowers next year - they need to be treated as one-off displays. If they were the plainer tulips though, the chances are that you will be OK.
