Once you know your exact dates and you have booked your hotels in Russia, every US citizen must get an invitation support letter from an accredited travel agency in Russia
Once you have your invitation (normally in the next working day), you should apply online for your russian visa application
You are now ready to go to the consulate general of Russia in New York to request your visa
9 East 91 Street, New York, NY 10128
Fax # of the consular section:..
Monday - Friday 9:00 a.m.-12:30 p.m.
Citizen of ..... can apply for their Russian visa here
Address and information on visa application at:
Address and information on the representatives of Russia in USA
Read: Russian visa for American citizens