Let's make sure we get the idea of formal fallacies by putting them along side some valid forms. (I'm reviewing some material from T2.1 because I don't think that is clear enough.)
But let's remind ourselves first about logically equivalent statements.
We've seen that
1. If there is fire, then there is oxygen
2. There is fire only if there is oxygen.
...mean the same thing. They are logically equivalent ways of saying that the presence of oxygen is a requirement for fire.
Drag the labels to their forms (and into the gray areas). Remember that "then" or "only if" come to the same thing.