Before we start drawing the streets, select View, Grid from the menu. A background grid will appear that you can use a guide as you draw the streets.
If you select View, Edit Grid you can change the color and spacing of the grid. You can also specify that the grid appears over the objects.
The color is only so that you can see it clearly as you draw. The grid does not appear at run time. You can also select Snap to Grid if you want to line things up along the grid.