You can create an Amazon Machine Image or AMI for your existing EC2 instance. The AMI will allow you to launch a fresh EC2 instance using the AMI as a template. You can also share the AMI with other AWS accounts.
To get started, it is best practise to stop your instance before you start. So right click your instance and click stop
When the instance has stopped, right click it again, click image and then create Image
Give your Image a name, a description and then click create Image
In the screen that appears click the ami ID.
You will now see your image creation as pending.
Once the ami is marked as available you can then launch it as an EC2 instance.
A full video tutorial can be found here: