A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Well, I can't comment on what they may have sent you to, but the first point they should have clarified is that a check box can't be added to a cell in any version of Excel. What you can do is draw Check Box Form Fields on a worksheet which can be linked to a cell. That will return either True [checked] or False [unchecked] in the linked cell. The process, itself, isn't much different than in any other versions that support them.
You can do that by going to the Developer tab of the Ribbon. If it isn't displayed in your installation, go to Excel> Preferences> View then check the box for Developer tab at the bottom of the preferences pane. Once you create the control, right-click it & select Format Control to access its properties.
NOTE: Unfortunately, it needs to be emphasized that the controls are broken in the current [15.17] version of the program... they can still be created but they won't work in Excel 2016 until Microsoft supplies a fix in a future update.