Hi@akhtar,
You can create a Route Table in the VPC using the create_route_table() method, and then create a new route which will be attached to the internet gateway you created earlier, to establish a public route.
# create a route table and a public route
routetable = vpc.create_route_table()
route = routetable.create_route(DestinationCidrBlock='0.0.0.0/0', GatewayId=internetgateway.id)