Free, printable immigration forms are available from the United States Citizenship and Immigration Services website. You can download and print the forms to fill them in by hand, or you can fill them out using Adobe Reader software.
If computer access is an issue, USCIS can mail copies of any form you require. These forms are always free. The website contains links to citizenship and green card applications as well as employment authorization and verification forms. Although all of these forms are free to download and print, many of them have an associated processing fee which is due upon submission to USCIS.