VLookup To Work For Multiple Ranges On Different Sheets

Code:
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Intersect(ActiveCell, Sheet8.Range("C16:Y1000")) Is Nothing Then Exit Sub
Dim rw As Integer
Dim arw As Integer
rw = 16

[Code] .....

As you can see, my code is located in the sheet8 worksheet object. Now, I have a few questions about this. Because I am located in the sheet8 worksheet object does that mean my code can only work in sheet8, i.e., the following won't work because I am in a Sheet8 worksheet object?

Sheet10.Range("B12) = ..... ....... .....

This is not returning a value in Sheet10? My question is how do I make my code return a value in Sheet10?