Hmmm..OK.. here goes...First make bsnl modem to dial (ppoe) i hope you know how to do that, if not i'll explain that later...enable dhcp in the bsnl modem(i think its enabled by default, just cross-check)... Then connect your
Linksys router to any pc to configure it, go to the login page type user name and password(i think its admin/admin or admin/password or admin/(blank).. there make sure you disable dhcp and set to bridged mode(not dialed mode cause bsnl modem is doing the dialing)...Thats it for the configuration.. Then connect your bsnl modem to the first LAN port of the linksys router..make sure you connect it to the LAN port and not the WAN port.. the WAN port will be seperated from the LAN ports, so you should be able to make out the difference..Then connect other pcs to the other LAN ports of your linksys router... THe wireless configuration is standard, just like any other router.. set the SSID and better set a good WEP key.. and choose a channel like 6 or 11.. and you should be good to go!!All the best!!!!