rmtc:
thanks for helping me bro, yes there is a switch on the bluetooth shield near the red led and green led, on the switch it says hc-05 and hc-06 , i always set it on hc-05.
I can hardly believe what I'm reading here. What you are telling me is that that switch is for the convenience of the manufacturer, not your convenience. In the meantime they give you nothing to make your life easier, and it does rather suggest that they never expected to sell many. I would be glad to hear where you got it from. Leave it on HC-05 as you suggest.
is d0 and d1 is the rx,tx that i can see on the shield?
Yes, they are the normal hardware serial pins for Uno and Mega, i.e. the shield will work fine on both.
can you pls teach how can i go to at mode
if theres a code or anything 
I'm afraid I have no idea of the proper way to set this up for AT mode. Hence, at the risk of sounding flippant, my best advice is to ditch it and get a proper module, made by somebody who knows what they are doing. But you really need to check out the manufacturer on this as there is a faint possibility that they aren't as stupid as I think they are, and the module is already set up as master!
The best basic AT mode procedure I know of is here
http://www.martyncurrey.com/arduino-with-hc-05-bluetooth-module-at-mode/
Currey is a bit of an AT-mode eminence gris on this forum, and Cantin is sure to have stuff on this as well. For the really basic stuff, you might find the following background notes useful
http://homepages.ihug.com.au/~npyner/Arduino/GUIDE_2BT.pdf
http://homepages.ihug.com.au/~npyner/Arduino/BT_2_WAY.ino
but it does not cover AT made for HC-05, or Arduino<>Arduino comms.