An end is simply a new beginning
This may be the end of the book, but it is also the beginning of your journey into software architecture and design. No matter who you are, I hope you found this to be a refreshing view of design patterns and how to design SOLID web apps.
Depending on your goal and current situation, you may want to explore one or more application-scale design patterns in more depth, start your next personal project, start a business, apply for a new job, or all of those at the same time. No matter your goal, keep in mind that designing software is technical but also an art. There is rarely one right way of implementing a feature, but multiple acceptable ways of doing so. Experience is your best friend, so keep programming, learn from your mistakes, and move forward. Remember that we are all born knowing next to nothing, so not knowing something is expected; we need to learn. Please ask your teammates questions, learn from them, and share your knowledge with others...