Instr function used in an if statement to find text in a row - excel

Question

In this code I am trying to have the user select a range in a row. If the row contains "HOL" the message box show will show a message.
The way the code is right now when the user chooses one cell that contains "HOL" the message appears when the user chooses multi cells in a row an error Runtime error 13 appears. This is the if statement that I am having problems
I have tried different range select methods but I am not familiar enough with coding yet to understand my error.
' Highlight_SKL Macro
' This macro will highlight leave dates for entry
Dim rng As Range
Set rng = Range(Selection.Address)
If MsgBox("Are you sure you want to submit day of SKL", vbYesNo) = vbNo Then Exit Sub
If InStr(Range(Selection.Address), "HOL") Then MsgBox ("You are entering a SKL date on a Federal Holiday")
With Selection.Interior
rng = "=1"
.Pattern = xlSolid
.PatternColorIndex = xlAutomatic
.Color = 250
.TintAndShade = 0
.PatternTintAndShade = 0
End With
End Sub
When the user select a row that contains "HOL" a message box appears and lets them know.

Answer 1

Use a wildcard MATCH for a selection of one or many cells.
If Not IsError(application.match("*HOL*", Selection, 0)) Then _
MsgBox "You are entering a SKL date on a Federal Holiday"

Answer 2

The below code use for each loop to loop each cell of the selection to avoid errors.
Option Explicit
Sub test()
Dim rng As Range, cell As Range
Set rng = ThisWorkbook.Worksheets("Sheet1").Range(Selection.Address) '<- Change sheet name if need
If MsgBox("Are you sure you want to submit day of SKL", vbYesNo) = vbNo Then Exit Sub
For Each cell In rng
If InStr(cell, "HOL") Then MsgBox ("You are entering a SKL date on a Federal Holiday")
With cell
With .Interior
.Pattern = xlSolid
.PatternColorIndex = xlAutomatic
.Color = 250
.TintAndShade = 0
.PatternTintAndShade = 0
End With
.Value = 1
End With
Next cell
End Sub