its not too complicated, u need to make a "Dialog" it involves variables, and triggers, and it can be quite large depending on what u need. To make a simple one:
Events- Your event
Conditions-
Actions-
1.Set Variable: Creat a "dialog" variable with the name you choose
2.Create dialog button for "dialog" labelled 'you choose'
3.Set a new Dialog Button Variable as last created button.
4.Create as many as you need.
5.Show "dialog"
Now, you need another trigger if a button is klicked.
lets say, you named button1 as Orc
Events-
A dialog button is clicked for "dialog"
Conditions-(Clicked dialog Button) equal to "orc"
Events-
Hide "dialog"
(your events here)
Hope it helps..
You need to create many triggers for all the different buttons.