Here's an example. On clicking the brick, it first checks if the client's class is 'uppa'. If it's not, a message will pop up saying "Only uppa class people can click me!"
If the client's class is uppa, it will display the client's experience variable. You will need at least 10 experience to get the last message and get +1 experience.
I included an event save if you want to load it in game, assuming you have the event saver addon.