Write to last modified col in db

[Rani]

What is the best way to use this code and fill last modified column in the db field.
LCase(Replace(Request.ServerVariables("AUTH_USER"), "WLT\", ""))

I have filled other fields in the db but not sure how would i fill the last modified with the above pc of code. I have no idea what this pc of code does. Pls advise wht to do. thanks/Rani