Adding custom date when importing Excel file

Hello,
I'm trying to figure out how to do something like that. There is one SQL table MYRECORDS with fields below:

ID (int - autoincremental)

COL1 (nvarchar)

COL2 (nvarchar)

COL3 (nvarchar)

EXPORTDATE (datetime)
There is also an Excel file with columns:

COL1

COL2

COL3
I'm using an import page to load records from Excel file to this table. This part is working fine. But now, the final procedure should work like this:

1. On import page I will choose any date from calendar form. How to add this part?
   
2. Then on the same page I will choose the file to import.
   
3. Then I will press Import button.
   
4. After inserting, I will get all records from Excel file in SQL table.
   
5. All records in SQL table should have the same date (choosen at point 1) value in EXPORTDATE field. How to do that?
   Thanks in advance for any tips.
   
   Brgds
   
   Mariusz