Very clear - copying the text in case thread gets archived:

The order of distributions from a ROTH IRA is:
1) Regular contributions.
2) Conversion contributions on a fifo basis.
3) Earnings on contributions.

Once the Roth has been in existance for 5 years you can withdraw any regular contributions without penalty. Even contributions made the previous year.  (Actually you can do this at any time)

Each conversion contribution starts its own 5 year clock (which is why the money is considered to come out in fifo style). Once a particular conversion contribution is five years past those funds can then be withdrawn without penalty.

Hope that clears the confusion for you.