If statement user created function

so I am so new to VB it's lame but I have the following code

Function Adjust(x)
    
If (Range("Ref!$A$16") = 2 And Range("Ref!$A$29") = 1) Then
    
    If Range(x) > 20 And Range(x) < 86 Then
        x = x + 3
    ElseIf Range(x) > 87 And Range(x) < 453 Then
        x = x + 3
    ElseIf Range(x) > 454 And Range(x) < 807 Then
        x = x + 3
    Else
        x
    End If
    
ElseIf (Range("Ref!$A$16") = 3 And Range("Ref!$A$29") <> 1) Then

    If Range(x) > 20 And Range(x) < 86 Then
        x = x + 3
    ElseIf Range(x) > 87 And Range(x) < 453 Then
        x = x + 29
    ElseIf Range(x) > 454 And Range(x) < 807 Then
        x = x + 136
    Else
        x
    End If
    


ElseIf (Range("Ref!$A$16") = 3 And Range("Ref!$A$29") = 1) Then

    If Range(x) > 20 And Range(x) < 86 Then
        x = x + 6
    ElseIf Range(x) > 87 And Range(x) < 453 Then
        x = x + 132
    ElseIf Range(x) > 454 And Range(x) < 807 Then
        x = x + 639
    Else
        x
    End If
    
Else: x

End If


End Function

My question is I know it's not correct. "x" is going to be a cell in the range C11:C96 from the provided worksheet. C11:C96 will eventually be referenced on worksheet1 in column A.

So I'm trying to make this work but I have no idea how to make excel let me use this function nor do I know if the code is correct.

can anyone help me out?

Thanks a million