Buckit automatically put expenses into different categories, for example, a transaction at Giant Food (your local grocer) is classified as a Food and Drinks expenditure. In the case where you bought gas at the grocer (it can be done!) you can classify that spending as "Transportation" instead
You can adjust the category of expenditures to fit your needs by re-categorizing a transaction. This is really easy to do, just click on the transaction, select categorize and label the category you want for that transaction. That's it.
This can be really helpful as you start looking at your spending by category on the My Money screens. It will give you a good sense of your own spending habits over time.