Using funds in your Health Savings Account is easy:
Typically an HSA will provide you with a checkbook or debit card. When you pay for a qualified medical expenses, use the debit card or check to make the payment.
You do not need to get approval from the HSA administrator when you use funds in your account.
You do not need to submit receipts to the HSA administrator, although you should save them just as you keep receipts for other items that are deducted from your taxes.
NOTE: You must establish the HSA before you incur medical expenses otherwise the expenses will not qualify.