I have followed these steps
https://msdn.microsoft.com/en-us/library/dn284011(v=msads.10).aspx
At step 10 when i press ok i get a message that says
An Error Occured
That's because you cannot create new application and adunit in PubCenter for now. PubCenter has been integrated into Windows Dev Center.
Note: You will no longer be able to create ad units or new app promotion campaigns in pubCenter. For information on how to create ad units in Dev Center, see Monetize with ads. For information on how to create app promotion campaigns in Dev Center, see Create an ad campaign for your app. Please see https://msdn.microsoft.com/en-us/library/windows/apps/mt186437.aspx for details