Where to buy a 1 year T-bill?

Excuse me, I'm interested in purchasing a one-year Treasury bill, but I'm not quite sure where to go to make the purchase. Could you please guide me on the steps I need to take? Do I need to go through a broker or a financial institution? Are there any online platforms that I can use to buy T-bills? Also, what's the minimum investment amount required for a one-year T-bill? I'd appreciate any information you can provide to help me make an informed decision. Thank you.