The best place to start when using any new tool is to create a "Hello World" app — the simplest possible app that you can create. Let's do that right now.
Create the Hello World App
From the Admin Portal click on Create App
Enter a name for the app and hit Next (for now you can ignore the region selector and just it leave it on US).
Select the "Source control" you want your new app to use and hit Next (for now you should select "Revisions" and "JourneyApps", for more on GitHub integration please reach out to your Customer Success Manager).
Select the "Blank" app template and hit Next.
After hitting Next, OXIDE will get your new app all set up for you and you will get navigated to the Overview for your app: