If you do not learn Hindi grammar, you will most likely never learn to speak the language fluently. Although kids learn to speak well without first learning the grammatical rules, adults generally will not be able to learn this way.
Visit walawali to learn genders of Hindi nouns and keep track of your progress.
Lesson one starts with the basics and many of the remaining lessons build on all the previous lessons. In each lesson you will find an explanation of the grammatical rules, a new vocabulary section, and some practice sentences to check your understanding.
Although this is not a complete grammar course (yet), learning the lessons given will get you far enough to have some basic conversations, if you learn them well. Expect to see more lessons coming in the future.