Making and publishing your own gem is simple if you use the tool Bundler.
Gardening is one of my hobbies, I like to grow tomatoes, cucumbers and peppers in my garden. Building an app is a lot like growing a garden, you need to invest lots of time and overcome many obstacles before you can enjoy the fruit of your labor; you will not be able to learn everything about it by reading books, you need hands-on experience, you need to learn from your mistakes. The more apps you build, the more skills you pick up.