Start with the basics. Then learn one thing at time. A full web app will have a set a modules: database handling, migrations, routing, templating, etc. Don’t try to learn everything at the same time.
These two sites are a good start:
Unfortunately the Oracle database don’t have an excellent support from Golang. I’d suggest you to start with MySQL or PostgreSQL to learn how to use a database in Go (since they have great support for Go) and only jump to Oracle later.
Installing the Oracle driver for Go is a bit more complicated and other DB, you can take a look at this guide to do it.