VBA Function: Filtering a Dynamic Array

I'd like some help creating a VBA Function.

Specifically, I need to create a VBA function which goes into a column within a dynamic array and then provides a list of unique fields in a seperate worksheet.

Any advice would be much appreciated.

Specifically, I would like to create a unique filter for the date in Column C and the data starts in cell C6. But the starting cell can be C5 or C7 or C8......depending on how many Groups I have inserted in the top rows.