Entering a days data manually is easy. Simply click on the date you want to add and then go to Daily Reconciliation. Click on Manual Input.
Click on Edit. Enter your data in the screen shown below, using the tabs to enter in SKU & Fuel Sales (Shift Sales Tab) and then click the stick readings tab to enter those and then the receipts tab. Be sure to click on the save icon at the top when you are done. The tabs are shown circled in red below.