Question Tic Tac Toe

[Fuz]

Sort of Tic Tac Toe, 3 connected is a win.

I allready drew a grid with .DrawLine of 10x10, and I found my mouse coordinates by

TextBox1.Text = System.Windows.Forms.Cursor.Position.X.ToString() & " " & System.Windows.Forms.Cursor.Position.Y.ToString()

But I don't know how to know in which box of the grid it is.

Thanks!