If you're using Android Studio for Windows to create a release keystore and signed .apk, just follow these steps:
1) Build > Generate Signed APK
2) Choose "Create New...", choose the path to the keystore, and enter all the required data
3) After your keystore (your_keystore_name.jks) has been created, you will then use it to create your first signed apk at a destination of your choosing
I haven't seen a need to use the command tool if you have an IDE like Android Studio.