Try using the Worksheet.Protect
method, like so:
Sub ProtectActiveSheet()
Dim ws As Worksheet
Set ws = ActiveSheet
ws.Protect DrawingObjects:=True, Contents:=True, _
Scenarios:=True, Password="SamplePassword"
End Sub
You should, however, be concerned about including the password in your VBA code. You don't necessarily need a password if you're only trying to put up a simple barrier that keeps a user from making small mistakes like deleting formulas, etc.
Also, if you want to see how to do certain things in VBA in Excel, try recording a Macro and looking at the code it generates. That's a good way to get started in VBA.