The U.S. Citizenship and Immigration Services (USCIS) web page provides information about a variety of topics concerning legal immigration to the United States, including the Case Status Service, where you can check the status of your case. Also available are a number of the most commonly required USCIS forms and an up-to-date list of the fees associated with them. Because the fees periodically change, you may want to visit this section of the USCIS web site before completing any application to the agency.
Other topics pertaining to immigration, including citizenship, are discussed in the Immigration Services and Benefits section of the USCIS web page. Foreign adoption information is available on the State Department web site.