If [field1] 'Yes', Set [field2] To 'Open'

If [field1] 'Yes', set [field2] to 'Open'. That's what I'm trying to do.

Field 1 is a combo where I choose between 'Yes' or 'No' from an outside table.
Field 2 is a textbox that I don't have showing on the form.

What code do I put into the 'AfterUpdate' of Field 1 when I change the value to either Yes or No?

I can see it all in C++ code...

{
if Field1==Yes, then Field2==1
else if Field 1==No, then Field2==0
}

But I don't know how to translate to the VBA.