In order to gain push access to the repository you will have to create a username on the hosting site and upload a public ssh key. Have the key ready as it will as for it when you sign up. If you have a key already you can register your username here and give your username, email and public key. There's no password involved with the account, the only password is the one you put on your ssh key when you create it, if you choose to do so. Its not like there is sensitive material involved, so dont feel compelled to use a password.
In order to generate an ssh key will require ssh be installed. Most linux distributions will have this already. Simply type in:
ssh-keygen
and your key will be generated. Your public key will be in ~/.ssh/ in a file with a .pub suffix, likely id_rsa.pub or id_dsa.pub. Open the file in a text editor (turn off line wrapping if its enabled), and copy/paste the key into your browser. Its important that the line not be broken over multiple lines.
Once your account has been created, send an email to the address found by the Owner tag on the jnode repo website, which is here. Once you are added you will need to configure your git configuration to use the new push url with your username.
When you originally cloned the repository the configuration setup a remote named origin that referenced the public repo using the anonymous pull url. We'll now change that using git-config.
git config remote.origin.url git@github.com:[user]/jnode.git
Of course replacing [user] with your username, which is case sensitive.
Now you should be setup. Please see the page on push rules and etiquette before continuing.