hi jayant a very gud startup… you can use the tutorials given on this site, they are based on atmega16 but works for atmega8 too…
here i am sending you some links which might be help ful for you since you are a starter….
how to start working with avr studio
http://www.engineersgarage.com/tutorials/avr-studio4-working
AVR tutorials
http://www.engineersgarage.com/embedded/avr-microcontroller-projects