Notification of a class-action lawsuit: Notice is given by the prosecuting attorney to all eligible parties. This is done by mail or publication. If you do not receive notice and the deadline for participation in the class passes, you have no recourse in this particular lawsuit, meaning you have no right to damages won in the original case. A good example: you have moved and have not yet notified the post office of your forwarding address. The court only requires "best notice under practical circumstances" be given.
Filing your own class action lawsuit or an individual suit: Unless your personal damages are very large ($100,000+), you will most likely need other parties to induce an attorney to take the case on a contingency basis.
It is possible to bring a competing class or an independent court action against a company. The relative merits of each course should be discussed with counsel and will depend on monetary amounts, number of parties involved, etc.
The general rule is, the larger the class (the more parties involved), the easier it is to get competent counsel involved on a contingency basis; and the greater your chance of recovering damages.
A class-action lawsuit is filed when different people combine their lawsuits because the facts of the case are so similar. This is designed to save court time, and allow one judge to hear all the cases at the same time and make one decision binding to all parties.
If the court agrees to certify the case as a class-action lawsuit, that means the court agrees there is a problem where all people in the same circumstances should get redress. All class members are supposed to have equal input and rights to any monies or remedies ordered by the court.