Try this
Code:
Sub Macro2()
Dim str As String, aCell As Cell
Selection.InsertColumns 'or InsertColumnsRight
str = InputBox("What do you want in each cell?", "Feed Me", "Hi mum")
For Each aCell In Selection.Cells
aCell.Range.Text = str
Next aCell
End Sub
If you have a userform open and you want the text value to come from the field you could change the str line to
str = Me.txtColumn