Set Margin to Widget in Flutter

This is how to set top margin:

              Container(
                  color: Colors.blue,
                  margin: EdgeInsets.only(top: 20.0),
                  child: Text(
                    "My widget",
                  ))

In a similar way you set the bottom margin like so:

              Container(
                  color: Colors.blue,
                  margin: EdgeInsets.only(top: 20.0),
                  child: Text(
                    "My widget",
                  ))

To set the left or right margin simply just change top to left or right inside the EdgeInsets.only function.

Set the left margin

EdgeInsets.only(left: 20.0)

Set the right margin

EdgeInsets.only(right: 20.0)

To set margin for all sides use the .all

              Container(
                  color: Colors.blue,
                  margin: EdgeInsets.all(20.0),
                  child: Text(
                    "My widget",
                  ))