Putting the Bank in the To column with a positive value will give you a positive Bank balance (the money has gone To the bank, therefore the balance in the bank goes up)
Putting the Bank in the From column with a positive value will give you a negative Bank balance (the money has come From the bank, therefore the balance in the bank goes down)
You only enter one side of the transaction for opening balances.
Add a comment e.g. "Opening balance" as a note to remind yourself what it was in the Comment field.