https://www.irs.gov/publications/p590b
If the cash you received was from an IRA, which would make it a non spouse inherited IRA, things you must know are whether it was a Roth account and how long the account was open or if it was a traditional IRA. As for paperwork involved, you may see a form 1099-R for the tax year of the received funds, if so, file it with your tax return and it will show a taxable amount, if any.
