主题：绘制图片,文字怎么旋转90度

Dim imgback As image = getimage("C:\图片.jpg")
Dim bmp As new bitmap(imgback.width, imgback.height) 

Dim g = graphics.fromimage(bmp)
g.DrawImage(imgback, 0, 0, imgback.Width, imgback.Height)
Dim fnt As New Font("宋体",12,FontStyle.Bold)
Dim msg As String = "Foxtable"
g.DrawString(msg,fnt,Brushes.Gray,100,347)
bmp.Save("f:\新图片.jpg")
bmp.dispose
如题:怎么将写入图片中的的文字"Foxtable"旋转90度,请教老师,谢谢