How you add transactions from an electronic statement to the register depends on whether they affect other transactions that are already in QuickBooks or not.
They may affect existing transactions: If a transaction is a payment from a customer, you may need to mark an invoice as paid. If it is a payment to a vendor, you may need to mark a bill as paid. Or, if it is a deposit of customer payments that you received in QuickBooks, you need to record the deposit.
They do not affect anything: None of the transactions to enter are related to any bill, invoice, or received payment in QuickBooks.