Train reservation Xian-Beijing

We come to Xian at 24 th September and go by train to Beijing at 25 th September. Could you advise me when to start with reservation (for 3 Person). We stay in Xian in Han Tang Inn Hostel. Could you send all 3 ticket to this address or not and inform me about sending the ticket. I also want to know if have to pay 150 RMB for sending 3 ticket to Hostel in Xian (for each 150 RMB or 150 RMB for all 3 ticket).