We're going to start out with the event page. Select your sprite, and it should look something like this.
Let's click on "Change Variable," in the event command list. This is located in the first tab.
We'll need to set up our variable. We can use one variable for all messages. Let's name it 'messages." THe naming doesn't really matter, but it's always good to name your variables according to the purpose.
We need to have a number randomly selected, so set how many different messages you want possible for your event. (it counts zero as a number) I set it to four different numbers, 0, 1, 2, and 3.
Now, under the variable, let's click on "forks condition." This is located under the first tab.
We need to have one of these for every random number possible, but let's make one at a time. Select the variable, and the number. We need to start with 0.
Now that our first fork condition has been created, let's put the first possible message right here.
Define what the message is, then hit OK.
Now, under "else case," let's set up another fork condition.
Use the same variable, but increase the number by one.
Continue doing this until you have one for every possible number. In this case we have 0, 1, 2, and 3. Don't forget to put a different message in each fork condition.
Now we have random messages!