If you have the money for a book, you can find a large number of "conversational" Spanish books online. Studying from books of these types for 15 minutes or so a night can help increase your knowledge significantly.
Unfortunately, it's highly unlikely to become anywhere near fluent without classes, tutors, or just dumping yourself in a Spanish-only speaking area for months at a time. You can definitely learn a good amount of Spanish as far as tourism is concerned or basic questions and answers in conversation. But it takes persistence and time.
There's no way to learn Spanish entirely without understanding it's grammatical structures and rules to a nearly perfect extent. But if you keep persistent with a conversational book and study on your own, you can learn helpful phrases and pick up on some of the rules of the language, over time.