void setup() {
  //All pins are capable of Digital output, though P5 is 3v at HIGH instead of 5v
  pinMode(0, OUTPUT); //0 is P0, 1 is P1, 2 is P2, etc - unlike the analog inputs, for digital outputs the pin number matches
}

void loop() {
	digitalWrite(0,HIGH); //turn the pin HIGH (5v)
	delay(1000);
	digitalWrite(0,HIGH); //turn the pin LOW (GND)
	delay(1000);
}

NOTE: The internal pull-up (turned on by calling digitalWrite(0) after setting the pin to output, where 0 is the pin number) are much weaker (about 25k ohm) on an attiny then on an Arduino so the onboard LED interferes with them. If you need them you can use a different port, change your circuit to not need the internal pull-up, or cut the LED trace. For Model A this would apply to P1 for Model B this would apply to P0.(Model Identification)

int sensorValue = 0;

void setup() {
  //All pins are capable of Digital input
  pinMode(0, INPUT); //0 is P0, 1 is P1, 2 is P2, etc - unlike the analog inputs, for digital inputs the pin number matches
}

void loop() {
	sensorValue = digitalRead(1); //returns HIGH or LOW (true or false /  1 or 0)
}

int sensorValue = 0;

void setup() {
//You need not set pin mode for analogRead - 
//though if you have set the pin to output and later want to read from it then you need to set //pinMode(0,INPUT);  where 0 is the physical pin number not the analog input number. 
//see below for the proper pinMode statement to go with each analog read
}

void loop() {
  // The analog pins are referenced by their analog port number, not their pin number and are as follows:

	sensorValue = analogRead(1); //read P2 
	//to set to input: pinMode(2,INPUT); 
	//THIS IS P2, P2 is Analog Input 1, so when you are using analog read you refer to it as 1

	//sensorValue = analogRead(2); //read P4 
	//to set to input: pinMode(4,INPUT); 
	//THIS IS P4, P2 is Analog Input 2, so when you are using analog read you refer to it as 2

	//sensorValue = analogRead(3); //read P3 
	//to set to input: pinMode(3,INPUT); 
	//THIS IS P3, P3 is Analog Input 3, so when you are using analog read you refer to it as 3

	//sensorValue = analogRead(0); //read P5 
	//to set to input: pinMode(5,INPUT); 
	//THIS IS P5, P5 is Analog Input 0, so when you are using analog read you refer to it as 0
}

void setup() {
  //P0, P1, and P4 are capable of hardware PWM (analogWrite)
  pinMode(0, OUTPUT); //0 is P0, 1 is P1, 4 is P4 - unlike the analog inputs, for analog (PWM) outputs the pin number matches
}

void loop() {
	analogWrite(0,255); //turn the pin on full (100%)
	delay(1000);
	analogWrite(0,128); //turn the pin on half (50%)
	delay(1000);
	analogWrite(0,0); //turn the pin off (0%)
	delay(1000);
}