Welcome to Microsoft Q&A!
So is your account a developer account? If not, you might need to register a developer account first. You could refer to this document: Opening a developer account. This is the guide about how to register a developer account.
Besides, Microsoft Q&A is under the public preview, not all topics are supported. The supported topics are listed on the right top. For questions about publishing UWP apps, please ask in Submitting and Publishing Apps Forum.