To format the numbers (in columns D,E, & F) so that they all have 2 decimal places, select these columns (by clicking at the top (where the column letter is) and then chosing Format|Cells and then (on the number tab) click number and make sure that there is a 2 in decimal places.
I also check the use 1000 separator (,) because it makes reading bigger numbers easier (and makes finding errors slightly easier).
Then click OK.
The Format Cells dialog box could also be reached using the right mouse button menu and keyboard shortcut ([CTRL] and 1), or by using the toolbar icon, if you have chosen to put it on your toolbar.
Format the numbers in columns G and J so that they have no decimal places. (customers are normally only given a credit period consisting of whole days)
Format the dates in columns A, H & I in a similar way to above, choosing options Format|Cells and then (on the number tab) click date. Select the date format you prefer (choose one that doesn’t include the time)