Obtaining a waiver in US immigration involves several steps and requirements, varying depending on the type of waiver and individual circumstances. Will need a bit more info 

First of all, what type of waiver are you planning to file? for immigrant visa or non-immigrant visa? There are different types of waiver, I601, I601A, I-212. Each case is different and requires a particular evaluation to determinate what kind of waiver is required.

 A waiver is a legally binding provision where either party in a contract agrees to voluntarily forfeit a claim without the other party being liable.

You can use Form I-601 to apply for a waiver if you have been found to be ineligible to enter the United States as an immigrant