If you're unsure which type of IRA you have, you'll want to check the paperwork you received when you first opened the account. It will explicitly state what type of account it is.
Also, If you received a Form 5498 from the financial institution where you opened the account (the "custodian") -- showing any contributions you made in a given year -- then you can look at box 7 where the type of account is checked.
If you don't have any paperwork, then you'll need to contact the financial institution. They will be able to tell you.