You should be able to log in to your billing control panel by clicking HERE or by clicking "Hosting Login" in the top right menu on the site. (check the "log in to billing" box) or by going to https://service.aosoft.com
Once you have chosen the registrar that you will register your domain through, there are a few basic guidelines you may want to consider that can keep your domain safe and alleviate problems that can occur.
In some cases it is helpful to provide your staff or third parties access to your hosting account. The preferred method for this is to create a secondary user account with only the privileges required to perform the duties necessary to do their job. This can help to protect against accidental changes and make changes in staff access easier to manage.