HOW To Make METHOD in a Class?

[QuestionPlease]

I want to make an accelerate method that adds 5 to the speed field each time it is called?

Public Class CarClass
    Private yearModel As Integer
    Private make As String
    Private speed As Integer

    Public Sub New(ByVal yearM As Integer, ByVal make As String, ByVal speed As Integer)
        yearModel = yearM
        make = make
        speed = 0
    End Sub
    Public Sub SetYearModel(ByVal yearM As Integer)
        yearM = yearModel
    End Sub
    Public Sub SetMake(ByVal make As String)
        make = make
    End Sub
    Public Sub SetSpeed(ByVal speed As Integer)
        speed = speed
    End Sub
    Public Function GetyearModel() As Integer
        Return yearModel
    End Function
    Public Function Getmake() As String
        Return make
    End Function
    Public Function Getspeed() As Integer
        Return speed
    End Function

End Class