Go to Hindileaner.com. Select Hindi Basics under Lessons & Tutorials. Here you can view the Hindi alphabet, numbers and grammar rules.
Start with learning the alphabet. This will help learning all other information easier. If it helps, use a flashcard system where one side has the Hindi letter and the other side has the English letter. View the Hindi side and try to remember what English letter it is. It may seem like a long process, but eventually you will catch on.
Move to the Getting Started section, where you can learn Hindi words and phrases. Because you know the letters, it will be easier to understand the words. Again using flashcards may be helpful.
Sign up for the tutorial service that both websites have. These will give you in-depth tutorials that the free content can't give you. It will also help you learn how to piece together phrases and sentences. The Hindi Learner website charges 9.99 euros per month (as of September 2009) or 99.99 euros per year.
Study every day. The more you study the more the language will stick in your head and the more you will catch on.