Open the VBE (VB Editor) with ALT+F11. Then goto Insert-->Module.
In the new window that opens on the right you can add the following:
Private Sub HidePayroll()
Sheets("Payroll").Visible = xlVeryHidden
End Sub
Private Sub UnHidePayroll()
Sheets("Payroll").Visible = True
End Sub
You can run the code with F5. The Private keyword means that the code can't be run from the Macro list in Excel, so you'll have to be in VBA to run it. When you do this, make sure that you protect the VBA Project (Tools-->Options-->Protection-->Lock Project for Viewing). The next time you go to the VBE you'll need the password to get in.
You can also write code that evalutes the user name; if it's you then show the sheet, but leave it hidden for everyone else.