You go to your bank and ask to open a money market deposit account. That will give you daily access to your money in an insured account, but very low interest rates. Or you can go to www.TreasuryDirect.gov and buy 3 or 6 month U.S. Treasury bills, automatically renewing them when they mature at whatever the current rate is. But you can only get your money out when the T-bill matures.
Right now ALL safe yields are very low. Do not be tempted by promises of higher rates. That always involves more risk!