http://www.tp-link.com/en/article/?faqid=417 - in this guide everything is explained. What kind of problem do you have? Please exactly describe it.

I have W8951ND ADSL modem/wifi router and I also have WR2543ND wifi router. What kind of connection do you have between routers?

Please contact with your ISP and ask about network configuration. I don't know ISP in your country :(

I mean about your router configuration.

now i have a no idea how to use this ADSL modem as a WLAN router. Only like AP (Access Point).

The problem is that I can't enter a higher value, then it says "Your input downstream bandwidth is larger than max bandwidth!" I'm not sure for 100% but I think that is problem (bug) in firmware. I...