Incompatible aws region for subnet while creating Virtual Private Cloud (VPC).

[Franceshe]

Hi i would like to try using spot instance and follow the medium post(https://blog.slavv.com/learning-machine-learning-on-the-cheap-persistent-aws-spot-instances-668e7294b6d8#.9nrmbtnfk)
but I was stuck at the step of CREATING Virtual Private Cloud (VPC).
After
$. ec2-spotter/fast_ai/create_vpc.sh

I received error about parameter for subnet. Currently I set aws configure region as:Oregon (us-west-2), would that be the issue since it does not compatible with the following availability zones: us-west-2c, us-west-2b, us-west-2a, us-west-2d as the error claimed?
An error occurred (InvalidParameterValue) when calling the CreateSubnet operation: Value (us-east-1a) for parameter availabilityZone is invalid. Subnets can currently only be created in the following availability zones: us-west-2c, us-west-2b, us-west-2a, us-west-2d. usage: aws [options] <command> <subcommand> [<subcommand> ...] [parameters] To see help text, you can run: aws help aws <command> help aws <command> <subcommand> help aws: error: argument --subnet-id: expected one argument