I have a box in sheet named "General INFO"

If an "X" or "x" is entered into this box, then a hidden sheet named "Detail
INFO" becomes visible.

The code looks like this:

If Sheets("General INFO").Range("H45").Value = "X" Then
Sheets("Detail INFO").Visible = True
Else: Sheets("Detail INFO").Visible = False
End If

First, I don't knwo how to include "x" as well as "X"

Second, what sub do i put this under? there is no button to activate, i
just want this to always apply to the sheet. like as soon as x is entered,
the sheet is visible.

I was using
Private Sub Worksheet_Change(ByVal Target As Range)

but this created an error when i typed in other cells besides H45. This
probably easy for you guys, but i'm pretty new at this.

Thanks for any help
Steve