Alphanumeric issues

[ITDad]

I am taking a shot here because i am frustrated. I am sure this will sound basic to many of you but I am struggling with validation errors on my customer information form. Although I can check whether it is alpabetic or numeric it only checks the first character. If I enter "R3" for example it allows it. I know that I need to run a for next loop to check the whole string but I am not having any luck writing the code for it. Any help would be immensely appreciated. I found some code in this forum but don't know how to apply it to my project for class.
Here is what I found:

Public Function checkAlphaNumeric(strInputText As String) _
                                 As Boolean
Dim intCounter As Integer
Dim strCompare As String
Dim strInput As String
checkAlphaNumeric = False
For intCounter = 1 To Len(strInputText)
    strCompare = Mid$(strInputText, intCounter, 1)
    strInput = Mid$(strInputText, intCounter + 1, Len _ (strInputText))
    If strCompare Like ("[A-Z]") Or _
        strCompare Like ("[a-z]") Or _
        strCompare Like ("#") Then
        checkAlphaNumeric = True
    Else
        checkAlphaNumeric = False
        Exit Function
    End If
 Next intCounter
End Function

my two fields are txtName.Text and txtCity.Text thank you for a little hand holding.

[Hack]

Welcome to DevX

What are you trying to disallow? Alpha or numeric?