Do you have a separate Dynamics 365 v9 On-Premise deployment ready or is your plan to keep your same 2013 deployment and try to update it? It is usually best to start with a new deployment. Do you have a partner or developer that you work with that can assist with the customizations? Here is a link that will start you off with deployment options: https://docs.microsoft.com/en-us/dynamics365/customerengagement/on-premises/deploy/deploy-and-operate-dynamics-365-on-premises?view=op-9-0