I'm guessing but I think they would send you an email. They do have a list of winners. I haven't won anything except free S&H and 15% off when I played spin to win and they did send me an email regarding that. I can't play spin to win now because they don't have it on the website anymore, only on apps and I don't do that.
If you win a prize you will receive an email. Make sure emails from HSN will not go to your spam folder. You are given a time limit to claim your prize so respond promptly. I had to submit information for a tax form 1099. Good idea to print a copy of the prize you have won that shows the price/value of the prize. HSN will send you a 1099 next year for tax purposes as you must claim the value of the prize as income. You don't want to miss this important step because the irs will receive a copy of the 1099 form from HSN.