VBA - If a cell equals a certain value do a certain string otherwise do another string : I am trying to create a Macro. But am not entirely show how to get it to work. 

I want the Macro to run if cell A1 is not blank. If cell A1 is blank I want a msgbox to appear informing the user to fill in cell A1  before the Macro will work. 

IE 
in formula terms =if(A1<>"",do resest of macro,"Populate cell A1")

If someone could please help me create the condition do x or y depending on A1's value I would be most appreciative. 

I think it should work something like below  

    Sub Code ()
    If("A1")<>""""
    Goto String1
    Else 
    Goto String2

    String1:
    MsgBox "Populate cell A1"

    String2:
    Rest of code