Visit TreasuryDirect.gov and follow the account setup guide to register an individual or entity account.
Go to the "BuyDirect" tab, select your security (e.g., Bonds, Notes, or Savings Bonds), and enter the amount.
Marketable bonds have a $100 minimum purchase and must be bought in $100 increments. 2. Buying Through a Brokerage Buying a Treasury Marketable Security - TreasuryDirect