Can I write journal entries in romanji?

First notebook entry: Introducing myself Hello world! I am Alyssa W. I live in the United States of America. Currently I want to learn Japanese. I know a few words here and there. The basics of how to Speak it. However I would love to learn how to read it. Why do I want to learn Japanese? Well, its a beautiful language and I one day want to visit Japan. I also have a thing for learning languages.