The VBA would look something like this. Tried to think of a way that would look intuitive so you could move it around and change it if needed.
Code:
Dim strAddress As String
strAddress = [FName] & " " & [LName] & vbCrLf
If IsNull(FName1) = False And IsNull(LName1) = False Then
strAddress = strAddress & [FName1] & " " & [LName1] & vbCrLf
End If
strAddress = strAddress & [City] & ", " & [State] & " " & [Zip]
Me.txtControlName.Value = strAddress
The trick with reports is to determine where your controls reside within the report. You may have to do validation in one event handler (where say Fname is) and use another handler for another section to assign a variable to a control in a different section, like Page Header or Report Footer.
If all of the controls are in the same section all of the code in the example here will go in the same "Format" event handler.
You can create a handler by using the "Code Builder" or opening the VBA editor directly.
Highlight the section by clicking on it, the bar that runs horizontaly across the report's design surface. Go to the property sheet and click the Event tab. There will be a Format event. Click the ellipses (...) next to Format and select code builder.