First of all many congratulations on starting your journey with Oracle Database. I must say choosing Oracle 12c for starting is a very good choice. Working knowledge of Multi-tenant architecture will definitely help you with other advance versions line Oracle 18c & 19c. For the installation, I would suggest you take a look at the documentation here or you can watch the step-by-step process of the installation here in this video.
Hope this will help you. Thanks and all the best for the future.
You can install a Windows version of Oracle to a Windows PC.
Also be aware that you can install a virtualbox with an Oracle/Linux environment for your Windows PC too.
what is virtual box? what is different between this virtual box and others?
These types of virtual boxes are setup for particular purposes.
For example, for learning you should setup this virtual box, as it comes with alot of preinstalled software that you can examine: