Apply for the App Readiness Check, a validation of your solution, in the Manage My Apps tool. Respond to the Due Diligence questionaire. Both your Due Diligence check and your App Readiness Check must be approved in order for you to publish your solution, but you may begin to create your solution page in the meantime.
Shortly after you submit your App Readiness Check, you will receive a welcome email to begin the publishing process on SAP App Center. Follow the steps here.
Contact your Partner Service Advisor or your SAP Representative to apply for the Solution Readiness Check.
Once you have been approved to publish, contact App Center support and ask to have an account created for you on the SAP App Center platform.