You have to consider the sample space. In this example the sample space
is {1,2,3,4,5,6}
A simple event can be defined as a SINGLE outcome: Example getting a 3 OR 5 OR any other number from the sample space.
Now if you roll one dice & you want to get an even number (2,4,6), then you have chosen from the sample space three outcomes & this is a compound event
Equally, if you roll two dice and want to get "one" and "three," this is a compound event since you have chosen two outcomes from the sample space.
Mind you, if you want 5 And 5 when rolling two dice it's a simple event because you have chosen ONE outcome from the sample space.