It is very helpful to practice techniques in your free time from an instructional video in addition to attending classes. This is because when you learn a technique in class it is easy to forget it later. With an instructional video you can view the techniques as many times as you like therefore if you forget anything you can return to the video and re-learn. This is especially worthwhile if you have a friend to train with but you can also practice the techniques yourself as it is mostly a matter of memorizing all of the necessary steps.
If you are a white belt it is best to learn techniques from the Gracie Combatives DVD first which should help you progress to blue belt. If you do not wish to attend your local gym you can also be awarded your blue belt by Gracie University staff by submitting a test evaluation video of you performing the appropriate techniques.
Gracie University is a website designed by the Gracie family for Jiu Jitsu students around the world to use in order to learn from home. Students can register for free and get some lessons for free when they sign up. A student can purchase the individual techniques they want to learn and are then able to view them as many times as they like. You can view every Gracie Jiu Jitsu technique online and the techniques designed for white belts are also available on DVD.