This issue here is how to get a null value into a database field using the textarea's representation of no data.
In HTML, form fields do not support null values, only empty strings to represent no data. This means that in your 'Input Into' Or .AddNew commands you will have to handle for the difference between datatypes if you wish to place a null into a table's field.
Assuming you post the data to some script:
<%
'SomeScript.asp
Dim f1 : f1 = Request("taF1"

'taF1 is Text Area 1
Dim f2 : f2 = Request("taF2"

'taF2 is Text Area 2
Dim oCon
Function getDBSV(ByVal sData)
'Get DataBase String Value (getDBV)
If sData = "" Then
getDBSV = "Null"
Else
getDBSV = "'" & sData & "'"
End If
End Function
'Create Connection Object
'bla bla
oCon.Execute = "Insert Into tblX (fld1, fld2) Values (" & getDBSV(f1) & "," & getDBSV(f2) & "

"
%>