There are no special rules that apply at any age, some of the limitations for retired persons were recently removed. You just need to follow the ordinary rules.
To contribute to any IRA, you must have compensation from working. If you make a tax-deductible contribution to a traditional IRA, there is no time limit on withdrawals but the withdrawals are always subject to normal income tax no matter your age. There are no time limits on converting to a Roth IRA, although if you made a tax-deductible contribution, the conversion will be taxed.
Withdrawals of contributions from a Roth IRA are always tax free. Withdrawals of conversion are not taxable over age 59-1/2. Withdrawal of earnings is subject to ordinary income tax if it is less than 5 years since you opened your first Roth IRA.
I get the feeling you might be asking about a "backdoor Roth". If that is true, that's really a different subject. Reply with more details if you want a followup.
