android development, implementing google maps

Question

straight from http://code.google.com/android/add-ons/google-apis/mapkey.html it says:

To register for a Maps API Key, you need to provide an MD5 fingerprint of the certificate that you will use to sign your application. Before you visit the registration page, use Keytool to generate the fingerprint of the appropriate certificate. First, determine which key you will use to sign your application at release and make sure of the path to the keystore that contains it. Next, run Keytool with the -list option, against the target keystore and key alias. The table below lists the options you should use.

I dont understand the directions to do this. I tried on the terminal using:

keytool -genkey -v -keystore microjobs.keystore -alias mjkey -keyalg RSA

and entered name, and city state then:

keytool -list

but it returns:

keytool error: java.lang.Exception: Keystore file exists, but is empty:

What should i do?

Thanks.