using 74LS191 Counter and a 3x8 decoder (74LS138) to design circuit that light leds sequentaialy from D0 to D7 on the decoder use any extra gates.????

 

Use Google to get the data sheets for both IC's. That should answer your questions.

 

but i can't connect the circuit .............plz help me

 

Can you tell us why you can't make the connections? Do you have a lab to use, or are you supposed to make it work in simulation?