Click on any polyline or group of polylines to select them. Click the Draw | Change Boundary Type | Polyline to Polygon command to convert each polyline into a polygon. The polyline first and last end nodes are connected with a straight line. The new polygon uses the original polyline IDs and line properties. The default fill properties are applied to the new polygon.
Alternatively, polygons can be created from polylines by clicking the Draw | Edit Boundaries | Create Polygons by Locator or the Draw | Edit Boundaries | Create Polygons by IDs commands.
Polygon to Polyline
Snap All Polyline Segments