Adding Up Numbs

[Sicen]

Im developing a Text based Rpg on VB and Im fair new at it but I need help with a code i need and I dont know how to code it.
Race Selector

    Private Sub Button5_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
        HealthStat.Text = 15
    End Sub

Easily to see this code will add the number 15 in my Health Starter Stat but I need help with the second button which its my Class selector
Class Selector

    Private Sub Button6_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button6.Click
        HealthStat.Text = 
    End Sub

At HealthStat.Text = I need a code that will add like a number to the current 15 in my Health Starter Stat textbox. so can anyone help me? This might be a easy code for anyone out there but i couldnt think on 1