Go to Account and then choose Accounting > Transaction Export.
Use the filters on the left (or on the column headers) to filter to the transactions that you want to export.
There is a filter to show just transactions that have not been exported before – that is typically a good starting point for the export.
Choose Summary or Detail (on the top right of the grid) depending on if you want the donor information included in the export.
Click on Export to IIF.
Save the file on your computer.
When you login to Quickbooks, navigate to Import > IIF File and select the file that you saved on your computer.