I was asked to sign a contract at the time I was sitting in a chair waiting for my video session to start.  I said I should read this first, and was told that it only states that I am giving permission for my art to be used in the video, so I signed the three paragraph document without reading it.  I asked for a copy.  I went back a couple of days later for the completion of the video, and asked for my copy because it wasn't given to me when I was at the video shoot before.  When I got home I read it, and it stated that I was given the organization the right to use my art in videos, reproductions, and unlimited ways, etc. and I had no right for any of the  products sold from the video, and other reproductions from the art, and the items produced would be sold worldwide.  This was 6 days ago when I signed this.  Since I read the contract after the fact, and was given erroneous information about it said, and was asked to sign it while the three persons were ready to start, I feel that it was an unfair to me.  Now I want to renegotiate this contract, so that I can get some compensation, recognition, etc for the use of my artwork and set some limitations on how they will use the items reproduced, and I want the contract to be more specific on what they will be doing with the products they make.  Please give me helpful information on what to do.