How to connect phone filter on landline & adsl connection ?


I am going to get bsnl broadband connection.. I also bought the dlink 2750U router + modem. Though I have bought the modem on my own so bsnl will not provide installation.. I have a guide to install the modem.. Here is the link : Setting Up Your Wireless ADSL Modem Router ..But I don't know where to connect the phone filter ( i think the white square box). The modem includes a dsl and landline , a two way splitter... I also don't have an extra RJ11 cable which connects the splitter to landphone ....Where to get one ? pls help me...thanks...

Do I need the phone filter ( probably the white box) , if I use splitter ?