Verbal irony
Verbal irony is usually sarcasm. It happens when a person says something that is the opposite of true. In the example, one friend falls and another tells him he's doing a good job. The speaker does not actually think his friend did a nice job falling or that his friend is a genius because of this.
Dramatic irony is when the audience knows crucial information that another character on stage does not. For example, the balcony scene in Romeo and Juliet when Juliet is speaking. She does not know that Romeo can hear her, but the audience does. Situational irony happens when the opposite of what is expected occurs.