Public Class Form1

 

    Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged

        Dim a As Char

        a = ComboBox1.Text

        Select Case a

            Case "Kırmızı"

                Me.BackColor = Color.Red

            Case "Beyaz"

                Me.BackColor = Color.White

            Case "Mavi"

                Me.BackColor = Color.Blue

            Case "Siyah"

                Me.BackColor = Color.Black

        End Select

    End Sub