hey, i just recently started playing guitar and my amp doesnot have a good overdrive/distortion. Which pedal is the best for playing rock songs? Thanks
The best way to help your tone would be a better amp. Since you've just started though, I guess you don't want to spend a lot of money on gear just yet.

Depending on what kind of distortion you're looking for, there are tons of options. Overdrive pedals like the Digitech Bad Monkey (cheap) or Ibanez TS9 (not that cheap, but not very expensive either) will give you a medium gain tone for blues and rock. If you want a little more gain, the MI Audio Crunch Box is an affordable and great distortion. Of course, there are heaps of other pedals, so you really should go to a store and try out as many as possible.