Public Class Main

    Dim FirstName As String
    Dim Surname As String
    Dim Age As String
    Dim Day As String
    Dim Month As String
    Dim Year As String
    Dim CountryDropdownItem As String
    Dim Username As String
    Dim Password As String
    Dim ConfirmPassword As String
    Dim IsOkay As Boolean = True
    Dim ErrorCheck As Boolean = False
    Dim ChangeCheck As Integer

    Private Sub AgeInput_KeyPress(sender As Object, e As KeyPressEventArgs) Handles AgeInput.KeyPress
        If (Asc(e.KeyChar) >= 48 And Asc(e.KeyChar) <= 57) Or Asc(e.KeyChar) = 8 Then
            e.Handled = False
        Else
            e.Handled = True
        End If
    End Sub

    Private Sub FirstNameInput_KeyPress(sender As Object, e As KeyPressEventArgs) Handles FirstNameInput.KeyPress
        If Not (Asc(e.KeyChar) = 8) Then
            Dim allowedChars As String = "abcdefghijklmnopqrstuvwxyz-"
            If Not allowedChars.Contains(e.KeyChar.ToString.ToLower) Then
                e.KeyChar = ChrW(0)
                e.Handled = True
            End If
        End If
    End Sub

    Private Sub SurnameInput_KeyPress(sender As Object, e As KeyPressEventArgs) Handles SurnameInput.KeyPress
        If Not (Asc(e.KeyChar) = 8) Then
            Dim allowedChars As String = "abcdefghijklmnopqrstuvwxyz-"
            If Not allowedChars.Contains(e.KeyChar.ToString.ToLower) Then
                e.KeyChar = ChrW(0)
                e.Handled = True
            End If
        End If
    End Sub

    Private Sub InputButton_Click(sender As Object, e As EventArgs) Handles InputButton.Click
        FirstName = FirstNameInput.Text
        Surname = SurnameInput.Text
        Age = AgeInput.Text
        Day = DayDropdown.Text
        Month = MonthDropDown.Text
        Year = YearDropDown.Text
        CountryDropdownItem = CountryDropdown.Text
        Username = UserNameInput.Text
        Password = PasswordInput.Text
        ConfirmPassword = ConfirmPasswordInput.Text
        If FirstName = "" Then
            FNError.Image = My.Resources.RedX
            IsOkay = False
        End If
        If Surname = "" Then
            SurnameError.Image = My.Resources.RedX
            IsOkay = False
        End If

        If Age = "" Then
            AgeError.Image = My.Resources.RedX
            IsOkay = False
        End If
        If Day = "" Or Month = "" Or Year = "" Then
            DOBError.Image = My.Resources.RedX
            IsOkay = False
        End If
        If CountryDropdownItem = "" Then
            CountryError.Image = My.Resources.RedX
            IsOkay = False
        End If
        If Username = "" Then
            UsernameError.Image = My.Resources.RedX
            IsOkay = False
        End If
        If Password = "" Then
            PasswordError.Image = My.Resources.RedX
            IsOkay = False
        End If
        If ConfirmPassword = "" Then
            ConfirmPasswordError.Image = My.Resources.RedX
            IsOkay = False
        End If
        If IsOkay = False Then
            ErrorLabel.Text = "There is an error with this data you've inputed. Please change it to suit."
        End If
    End Sub

    'Detecting when the text is changed
    Private Sub FirstNameInput_TextChanged(sender As Object, e As EventArgs) Handles FirstNameInput.TextChanged
        ErrorCheck = True
        ChangeCheckTimer.Start()
        FNError.Image = Nothing
    End Sub

    Private Sub SurnameInput_TextChanged(sender As Object, e As EventArgs) Handles SurnameInput.TextChanged
        ErrorCheck = True
        ChangeCheckTimer.Start()
        SurnameError.Image = Nothing
    End Sub

    Private Sub AgeInput_TextChanged(sender As Object, e As EventArgs) Handles AgeInput.TextChanged
        ErrorCheck = True
        ChangeCheckTimer.Start()
        AgeError.Image = Nothing
    End Sub

    Private Sub DayDropdown_SelectedIndexChanged(sender As Object, e As EventArgs) Handles DayDropdown.SelectedIndexChanged
        ErrorCheck = True
        ChangeCheckTimer.Start()
        DOBError.Image = Nothing
    End Sub

    Private Sub MonthDropDown_SelectedIndexChanged(sender As Object, e As EventArgs) Handles MonthDropDown.SelectedIndexChanged
        ErrorCheck = True
        ChangeCheckTimer.Start()
        DOBError.Image = Nothing
    End Sub

    Private Sub YearDropDown_SelectedIndexChanged(sender As Object, e As EventArgs) Handles YearDropDown.SelectedIndexChanged
        ErrorCheck = True
        ChangeCheckTimer.Start()
        DOBError.Image = Nothing
    End Sub

    Private Sub CountryDropdown_SelectedIndexChanged(sender As Object, e As EventArgs) Handles CountryDropdown.SelectedIndexChanged
        ErrorCheck = True
        ChangeCheckTimer.Start()
        CountryError.Image = Nothing
    End Sub

    Private Sub UserNameBox_TextChanged(sender As Object, e As EventArgs) Handles UserNameInput.TextChanged
        ErrorCheck = True
        ChangeCheckTimer.Start()
        UsernameError.Image = Nothing
    End Sub

    Private Sub TextBox2_TextChanged(sender As Object, e As EventArgs) Handles PasswordInput.TextChanged
        ErrorCheck = True
        ChangeCheckTimer.Start()
        PasswordError.Image = Nothing
    End Sub

    Private Sub ConfirmPassworldInput_TextChanged(sender As Object, e As EventArgs) Handles ConfirmPasswordInput.TextChanged
        ErrorCheck = True
        ChangeCheckTimer.Start()
        ConfirmPasswordError.Image = Nothing
    End Sub

End Class


https://imgur.com/5yRToeh