The Variable option in the Destination panel contains a list of all the variables in the current publication. Select the name of the variable in which you want to store the randomly generated number:

In this example, the variable Dice will contain the randomly generated number – the variable could be displayed in a Text object so the user could see the result of their ‘throw of the dice’. Alternatively, you could create a Select Action with 6 Case actions – each case action could show a different animation or picture of a dice falling on the randomly generated number.

The Select Action