Add Windows User Name to Cell

[skydivetom]

Experts:

Attached is a sample spreadsheets which includes a validation process checking whether or not all five (5) questions have been answered (prior to closing XLS).

As part of the XLS closing process, the validation throws a message including the user's name plus the questions which are still unanswered.

Here's what I need some help with:
- Upon opening the spreadsheet, I want the Windows username (see validation message) automatically added into cell F1 (independent from having answered the questions). What VBA needs to be added which will insert the value? Once that's working column F will be hidden (merely for tracking who submitted what information).

Thank you,
EEH