You can file I-130 online or mail it in. once USCIS receives your case they will send you a receipt notice, following that you should receive an account access code. You would use the access code to setup your online account.

Once you mail your application to USCIS, they will receive it and send you receipt notices. They will send you an access code, where you can access your account.

I didn't request the code when I sent my application. Do they have any way to request the code now to create the online account?

@White Lilly you do not need to request it they will send you it automatically

Sorry for confusing. But i did not have a code or online account. I mail my applications and got the receipt notics but did not have access code.