Now Russian Railways has an English version of website http://eng.rzd.ru/ . It is very comfortable as it enables to buy the tickets on-line and to learn a lot of useful information.
To buy e-tickets you should enter the tab “Passengers”. Be careful, e-ticket control coupons, that you receive after payment, without a boarding pass are not valid as tickets. In order to receive your boarding pass, undertake electronic registration on the site (trains with the e-registration are marked by ER sign) or obtain a boarding pass on the ticket form at a ticket office or self-service terminal on the territory of Russian Federation. For detailed information about e-tickets, please, follow http://pass.rzd.ru/static/public/en?STRUCTURE_ID=5236
Russian Railways gives discounts for children, groups and other http://pass.rzd.ru/static/public/en?STRUCTURE_ID=737