I'm trying to program AtTiny13 using Arduino IDE. I have connected the atTiny to my PC using USBasp programer.
I want to write a simple blink application to test whether it works or not. Which pins should I blink?
You'll need an Arduino library that supports that chip, to make it appear in the Tools > Board list. The library docs will tell you which pins then correspond to which Arduino digital I/Os. From that you can decide which pin to attach an LED to (with resistor) and how to edit the blink sketch.
Because pins 0 and 1 (physical 5,6) are PWM's you should keep them for later ... and you still have A3 and A2 for analogWrite so, you should use Pin 2 (Physical 7, next to +5V) like this :
add this in the setup function
pinMode(2, OUTPUT);
And add this in your loop function:
digitalWrite(2,HIGH);
For reference : SparkFun's Help guide
Remember : Physical pin "1", reset, has a dot marked on it.