Once you have bound a form to your data source and set up the Item property with a record to edit (or put the Form into the DefaultMode of New), you should be able to achieve a two column appearance by changing the number of columns in the form customization pane. You can get to this pane by clicking on the "Data" area of the properties panel. Just below the data source dropdown, is a label for "Snap to columns". If you change this value to 2, you will see the form re-layout into 2 columns. Anything you want to be full-width, you can simply select that data card and dragging it's width to fill the form's width.
Please let me know if that did not answer your question.