If you really want a vba solution you can loop through a range like this:
Sub Check()
Dim dat As Variant
Dim rng As Range
Dim i As Long
Set rng = Range("A1:A100")
dat = rng
For i = LBound(dat, 1) To UBound(dat, 1)
If dat(i, 1) <> "" Then
rng(i, 2).Value = "My Text"
End If
Next
End Sub
*EDIT*
Instead of using varients you can just loop through the range like this:
Sub Check()
Dim rng As Range
Dim i As Long
'Set the range in column A you want to loop through
Set rng = Range("A1:A100")
For Each cell In rng
'test if cell is empty
If cell.Value <> "" Then
'write to adjacent cell
cell.Offset(0, 1).Value = "My Text"
End If
Next
End Sub