My question involves criminal law for the state of: California

I plead guilty to one count of wire fraud in the federal courts, central district of california. I have a restitution order of $150,000 and in my judgment it says that I am to pay 10% or a minimum of $500 per month. Most others that I know with much larger restitution are only obligated to $100 min per month. I make very little money right now and have NO assets at all. I know that I have to petition the court for a change to the payment, and that it requires the approval of the judge, but I don't know how to go about doing this and have been all over the website for the court and can't find a thing. Please help. I would like to handle this on my own and not use an attorney. Can't pay anymore attorneys!!