You have heard all the buzz on the new Power Platform and you have seen many posts on PowerApps/Model-driven Apps and Canvas Apps. You have also upgraded your Microsoft Dynamics 365 CRM instance to v9.x either On-Premise or Online, but you are not sure where to get started with apps!
This might be an interesting path:
1) If you are familiar with configuring Microsoft Dynamics 365 for CRM/CE then you might want to start by adding a Model-driven app to your one of your solution files.
A Model-driven app can be used in conjunction with what you are doing today (the classic menu) and there are some nice little short cuts to getting started. For instance you can create a Model-driven app using your current sitemap and/or a current solution file.
2) Once you get the hang of creating Model-driven apps (and there are some small little tricks) then perhaps it is time to dive into creating your first Canvas App. One of the differences between a Canvas App and a Model-driven app is that Canvas Apps tend to be focused on the Microsoft Stack first (think Microsoft 365) and Model-driven apps tend to be focused from a Dynamics 365 perspective (Think an app within a solution).
If you are empowered from learning online, you can get some nice step by step materials by working through some of the exercises on Microsoft Learning!