Tools -> Scheduler -> set focus on the Today's tasks pane -> Press Ins ert -> Your new task is created
General tab: Enter a discription and the first time the task has to be executed
Actions tab: Set the actions
Recurrence tab: enable 'repeat this event', se t the interval at 12 hours
Advanced tab: You can this this if your twice a day isn't every twelve hours
Links tab: Depending on the type of action you can use this
Categories tab: You don't really need this, it's merely to sort events when you've got a lot of them
I hope this helps.
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I'm just a user of The Bat! I don't work for Ritlabs.