The default VPC will work fine for this example. Once you are comfortable with creating databases, you may want to consider a VPC containing private subnets that you can use to segment your database away from the Internet and other resources (in the style of a three tier application). Either way, you'll need to note down the following:

• The ID of the VPC
• The CIDR range of the VPC
• The IDs of at least two subnets in your VPC. These subnets need to be in different Availability Zones, for example, us-east-1a and us-east-1b