How can a representative help me with my SSD SSI SSDI claim?

The following answer is from:

You may appoint a qualified person to represent you when doing business with Social Security. Use Form SSA-1696-U4, Appointment of Representative to tell us in writing about the person you appoint. Sign and date the document and send it to your local Social Security office

A representative generally cannot charge or collect a fee for these services without written approval from us. 

See Your Right To Representation for more information.

The following answer is Attorney Walter Hnot’s annotated response to the previous answer.

Basically, you want an attorney, who specializes or mostly deals with disability claims, that is both a state attorney, and a federal attorney.  Remember, non-legal people are called lay persons, or, “a person without professional or specialized knowledge in a particular subject.”  Lay people include disability advocates, non-legal representatives, friends, family members, ect…  Lay people are not trained for writing briefs, and are forbidden from practicing law, which means certain venues, such as district court, or circuit court, would hold them criminally liable and place them in prison for trying to represent you.  Remember one thing from this question.  The administrative law judge deciding your fate is an attorney, so lawyer up.