Not enough facts to determine what kind of a case it will be. Did you enter with or without a visa? If without you will need a waiver of unlawful presence (form I-601). As for what papers to fill out, it isn't always as easy as filling out a bunch of papers. Doing immigration cases on your own is risky.
Dhenu Savla, Esq.
Attorney fees depend on the attorney.
Filing fees are as posted on the USCIS website.
J Charles Ferrari Eng & Nishimura 213.622.2255 The statement above is general in nature and does not constitute legal advice, as not all the facts are known. You should retain an attorney to review all the facts specific to your case in order to receive advise specific to your case. The statement above does not create an attorney/client relationship. Answers on Avvo can only be general ones, as specific answers would require knowledge of all the facts. As such, they may or may not apply to the question.
The other attorneys are correct .... different fees, depending on a number of factors.
FORMER IMMIGRATION LAW PROFESSOR -- LEGAL DISCLAIMER: This answer is offered for informational purposes only. It does not constitute an attorney-client relationship.