The following is an example of using UpdatedBy and UpdatedDate properties to capture the current Windows user and current date.
Here the UpdatedBy is defined as a textbox and UpdatedDate is defined as a date.
In addition to enabling the Read Only option to prevent unwanted editing, the initial values for UpdatedBy are set as follows:
Value Type = expressionEvaluator
Value = system.environment.username()
Likewise, UpdatedDate property is set to Read Only with the following initial values:
Value Type = dateRegionalShort
Value = system.Date
UpdateDate and UpdatedBy.zip
A sample project is attached to help get you started.