It's vital that all your transactions be entered correctly for your books to be well balanced. QuickBooks Desktop is a great program able to help you keep track of sales and expenses so you can see the profit of your business. I can provide some information about importing bank transactions.
In order to import bank transactions to QuickBooks, I recommend checking out all the articles I've included below about bank connections. This series goes over connecting accounts, all the way to how to match and add the transactions so you can get them correctly affecting your books: