Search Down The First Column And Find Any Instance Of The Letter

I have this piece of code

Sub do()
Dim i As Integer
Dim x As integer
x = 5000
i = 1
Do Until i = x


If Cells(1, i).Value = "C" Then
ActiveCell.Select
Selection.Insert Shift:=xlToRight
Selection.Insert Shift:=xlToRigh

i = i + 1

End If
Loop
End Sub

I want it to search down the first column and find any instance of the letter C and shift it (along with the entire row) over two clumns to the right.