Accounts are identified by addresses that belong to private keys. To own an account, all you need is access to its private key. Always make sure that nobody except you gains access to your keys!
There are several methods to create accounts.
If you are running your own node on your machine, you can create a local account:
aergocli account new # Or using Docker: docker run --rm --net=host aergo/tools aergocli account new
To create an account without a node (aka offline):
aergocli account new --path ./wallet # Or using Docker: docker run --rm -it -v $(pwd)/wallet:/wallet aergo/tools aergocli account new --path /wallet
The output shows the address of your new account. It is saved in account/data.db in the given path.
You can export this new account:
aergocli account export --address your_address --password your_password --path ./wallet # Or using Docker: docker run --rm -it -v $(pwd)/wallet:/wallet aergo/tools aergocli account export --address your_address --path /wallet
The output shows the encrypted private key belonging to your address which can be imported in other wallets.